What do you mean?

どういう意味？・というと。。。・ということは？ = "Meaning?"

Examples:

1. A: With this poor result, I'm afraid we will have to make some big changes, starting with you.

B: What do you mean?

A: I mean you will have to find another job.

2. A: What do you mean, "The camera is gone"?

B: I mean it has been stolen.