Expresses the speaker's belief that something is impossible or there is no way that something is true ('there is no way that...').
彼がそんなことをするわけがないよ。真面目な人だし。
There's no way he would do such a thing. He's a serious person.
今日中に全部終わるわけがない。時間が足りない。
There's no way we can finish everything today. There's not enough time.
あの値段で本物のブランド品なわけがない。
There's no way that's a genuine designer item at that price.
Colloquially can mean 'easy' or 'simple' (e.g., 'it's easy to...').
この問題はわけがないよ。すぐ解ける。
This problem is a piece of cake. You can solve it immediately.
約束を守るのはわけがないことだ。
Keeping a promise is something that's easy (or straightforward).