(Do you) know what I mean?
Do you know what I’m saying?
Do you understand?
Are you following me?
Are you with me (so far)?
Have you got it?
Any questions?
Got it?
Showing Understanding
I see.
I understand.
I get it./I got it.
Gotcha. (Informal)
Expressing Lack of Understanding
I don’t get it.
(I’m sorry.) I don’t understand.
What do you mean?
I’m not following you.
I don’t quite follow you.
I’m not sure I get what you mean.
What was that again?