If something is all right/fine by someone, they agree that it can happen.

"I'd rather go later." "That's fine by me." “我想晚点去。”“我没意见。”

If it's all right by you, I'd like to leave now. 如果你不反对的话，我想现在走。

If you want to go in June rather than May, that's fine by me.

I'll ask Dan - if it's fine by him, we'll take the train there rather than drive.

"It would be better for me to go to the earlier performance." "Yeah, that's all right by me."

See also: by preposition