Meaningless; pointless. A colloquial way to say something has no meaning or purpose.
そんな方法は意味ないよ。もっと効率的なやり方を考えよう。
That method is pointless. Let's think of a more efficient way.
その議論は今の状況では意味無い。
That argument is meaningless in the current situation.
やり直すのは意味ないと思う。
I think redoing it is pointless.