Help yourself to something

意思是，请自便，随便吃，请随便吃点儿，自取，同义短语有make yourself at home，也是请自便的意思。例如

Help yourself to some cakes.别客气，请随便吃点儿蛋糕吧.

You are friends， so make yourself at home.意思是都是自己人，你别客气了。

help yourself同义词组

help yourself的意思帮助你自己，靠自己，自便，同义词组有count on yourself， make it yourself