If something is make-or-break, it is so important that it can bring a success or a failure for the different results.Make or break, 顾名思义“或成功，或失败”，表示一件事情至关重要，胜败在此一举。

Examples:

The make-or-break college entrance examination can always draw public attention. 具有胜败决定意义的高考总是能引起大众的关注。

It's a tough assignment, and it will either make or break her. 这是个艰巨的任务，对她来说胜败在此一举。