To have function/variable decleration keywords written on grammar or not to have?

Hello guys

I’m curious to know that should I have keywords like let’s say func or def in my grammar?
suppose everything is written the same, means that writing a def statement is like other normal statements for example print, so can I have a general statement rule and then in the target language for example in java I decide what to do with what keyword??? if not why it’s not ok?