"A well regulated militia being necessary to the security of a free state..."
We want to be a free country, so we accept the fact that we need a way to defend it from other countries. We will do this by providing a standing army and state regulated militias (National Guard units). We will provide these with the proper weapons to be able to efectively defend this country from other countries.
"...the right of the people to keep and bear arms shall not be infringed."
Now, since we already said we are going to have an army and state regulated militias, and we already said we are going to have to ARM these entities, we need a way for the common people to make sure they can defend themselves from the army and militias of the government in case the government decides to become tyrannical. We will do this by stating that the common people have a right to keep privately owned weapons and that the government has NO RIGHT to stop people from having them. The government has NO RIGHT to even make it difficult for people to have them. The govt has NO RIGHT to charge a license fee, nor to perform a background check, nor to keep a database of who has the weapons, nor to limit the number of weapons a person can have, nor to limit the type of weapons a person can have, nor to limit the amount of ammunition a person can have, nor to in any other way INFRINGE on the right of the people to keep and bear arms. In the simplest and most concise wording, this right SHALL NOT BE INFRINGED.
I hope this makes it clear enough for everyone.