We use this expression to say that we can’t understand the reason for something.
You can use this phrase in ………… language.
A: Honza should be here by now. It’s seven o’clock. We’re going to miss the start.
B: I just don’t get it. He told me he really wanted to come.
A: Pavla has decided not to do the exam.
B: I just don’t get it. She’s the best student. She could pass it any time.