|There are many terms to learn when it comes to guns. The best way to learn is to watch videos and to look up the terms.|
I started with 3 Youtube channels
Keep a list of all the terms you don't understand and using your favorite search engine try to determine what the term means.
Slowly, you'll learn what all the terms mean.
But, no matter how many videos you watch, you'll never really understand the terms until you buy and shoot one.