Just read the words.

When our founders wrote the Constitution and the Bill of Rights, they were written in plain, easily understood, English of the time.  Meanings have changed a little, but not that much. Simple language, so there was no mistake or misunderstandings.
Natural law is the basic philosophy that our founders chose to base our country on.  That and basic common sense English Common law.

In my earlier essay on the First amendment, the basic rights discussed were Life, Liberty and Property.  You, because you are a living human being, have these rights because they were given to you by a higher power, not because “government”, and this was self evident to the founders, and to most observant Christians.  Since those rights are given to you by “nature and nature’s God”, no one, person or earthly authority, has the right to take them from you.  You in turn have the right to protect your Life, Liberty and Property from anyone who would take them from you, even the government.  The Government has been given the power, by consent of the governed, to use violence to take those rights under certain circumstances (for example: criminal activity against other’s rights like robbery, rape or murder).  It was recognized that the people needed a way to protect those rights from anyone including the government, so they could not be taken by a whim of tyranny.

The Second Amendment reads:
“A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.”

Taking the words in the context and meaning of the founders is actually very simple.  They have left literally thousands of pages of debate and opinion that shows their intent to arm individual American citizens for both self protection and national defense.  There is no evidence, anywhere, to suggest otherwise, except an authoritarian view that the “hoi poloi” common people shouldn’t have arms, and need to be ruled by their betters.
The language is very simple, and easy to understand:
“A well regulated militia” means a militia that is well functioning, trained and well equipped as a modern, military force.  Made up of citizen soldiers, part timers, it was to be a “reserve force” for a very small standing army.  US Law Defines “Militia” very specifically:

UNITED STATES CODE
TITLE 10 – ARMED FORCES
Subtitle A – General Military Law
PART I – ORGANIZATION AND GENERAL MILITARY POWERS
CHAPTER 13 – THE MILITIA

§ 311. Militia: composition and classes

(a) The militia of the United States consists of all able-bodied males at least 17 years of age and, except as provided in section 313 of title 32, under 45 years of age who are, or who have made a declaration of intention to become, citizens of the United States and of female citizens of the United States who are members of the National Guard.

(b) The classes of the militia are —

(1) the organized militia, which consists of the National Guard and the Naval Militia;

and

(2) the unorganized militia, which consists of the members of the militia who are not members of the National Guard or the Naval Militia.

“Being necessary to the security of a free state” the militia, as described, is necessary to security to fight enemies of a free state both criminal and foreign. The militia itself, by definition includes Sheriff, and anyone he would deputize, and would also include the functions of the modern police force.  Now a “free state” in the context of the constitution, and natural law means a “nation state” that exists in “liberty” and protects the liberty of it’s individual people.  This would constitute a “state monopoly” on the use of violent force if only the militia was armed, but this:
“The right of the people to keep and bear arms” expressly negates that monopoly.  Rights are for individuals, there are no “group rights” or “collective rights”.  The “people” are the individual citizens.  “Keep and bear” means literally “own and carry”, not “rent from the government and keep locked in a safe”.  “Arms” in this context means the same arms that a modern military force, including a police force, would need in order to preform that function.
*** So specifically military arms.***
Because a “militia” serves at the pleasure and does the bidding of the government, it is a temptation to use it against the people.  Governments are made of fallible human beings, often power hungry and greedy, and often will use it’s military and police against the liberty and property of it’s citizens.  Protecting the people’s right to the same arms the military uses counters that, and as an added benefit arms the unorganized militia.
“Shall not be infringed.” is very specific language and does not leave the leeway that modern judiciary seems to want to regulate or license or deny the people access to military arms.  Because an infringement is any of those, or any attempt to control or deny such access by anyone.  Because it doesn’t say “congress” shall not infringe, or “state legislature” shall not infringe, or the “executive branch” shall not infringe, or “the judiciary” shall not infringe.

***All gun control is an infringement of the right to keep and bear arms.***

To paraphrase the meaning into modern English:
Because it is necessary to have a uniformed force to secure the liberty of a free nation, it is also necessary to make sure they don’t have a monopoly on the tools of violence needed to do that. Therefore, the natural right of the people to protect their life, liberty and property by force of arms if necessary must be insured by including an amendment to the constitution ensuring it, and protecting it from the government regulating it in ANY WAY.

In a nutshell, THAT is what the Second Amendment means.