"Your boys speak English."
Translation:Wasi chłopcy mówią po angielsku.
Please see an important difference between the options that mihxal wrote. The less used form "chłopacy" is masculine personal, exactly as it should. The a lot more used form "chłopaki" is for some illogical, unknown reason not masculine-personal, and therefore uses not masculine-personal forms ("wasze chłopaki, chłopaki były, chłopaki przyszły). That is an important exception one has to remember.
That would seem logical, however, the word "chłopaki" is a very strange exception and despite any logic it's treated like a 'not masculine-personal plural' noun. So it's actually "twoje chłopaki". Don't ask me why, I don't know.
I don't think there are any other exceptions like this one, luckily.
I'm not sure what you're asking about... "chłopcy" are also 'masculine personal plural', so the right form can be "wasi". That form has to match, so it can't be e.g. "wasz chłopcy", that would be ungrammatical.
But (standard) English is a weird language which doesn't distinguish between singular and plural 'you', so there's also a question of what you actually mean when you say "your boys". If it's singular 'you' (Your boys, John), then it's "twoi chłopcy", and if it's plural 'you' (Your boys, John and Susan), then it's "wasi chłopcy".