expression
all you have to do is; just; that's all
Used after a noun or the plain form of a verb/adjective to indicate that the stated thing or action is sufficient, and nothing more is needed. Often implies simplicity or minimal requirement.
ここに名前を書くだけでいいです。
All you have to do is write your name here.
お金は千円だけでいいの?
Is just 1,000 yen enough?