Talk about it
When someone tells you something important, it's a good idea to check that you have understood.
How do you do that?
What do you say?
One way to check that you have understood is to paraphrase what the other person has said. That means that you repeat what the person said but use your own words.
Listen to someone checking that they understand.
Are you going to the cafeteria? Could you get me a medium Diet Coke while you're down there?
So one medium Diet Coke. Is that right?
Checking your understanding means that you can be sure you know what the speaker is saying and the speaker can be sure that you have understood.
How about you?
Do you know how to check that you have understood? Do you do that often?