"Die Jungen trinken Wasser" - how do we decide the verb trinken ends with 'en'?
HI. You ask how "die Jungen" is equivalent to "sie" which is the pronoun for plural "they". Imagine a conversation like this: The boys are kicking the ball. Who are kicking the ball? They are kicking the ball. Once you have identified you are speaking about a plural noun you can substitute a plural pronoun when you refer to them later. Thus "sie" can stand for "die Jungen" Hope that helps a little. I don't know your Muttersprache - I hope my English is at the right level for you.