English is very idiomatic. There are many expressions we use every day that don’t make sense, even if you understand each word. It can be very confusing! Hang in there! You can learn them!

That rings a bell!/That doesn’t ring a bell.
These expressions aren’t about bells or ringing. So what do they mean?
If something rings a bell, it sounds familiar. If it doesn’t ring a bell, it doesn’t sound familiar.
If something rings a bell, it might cause you to remember something. The memory might not be clear.
If something doesn’t ring a bell, it doesn’t cause you to remember anything. You don’t think you have heard about it.
In this expression, the bell is your memory.
If you think about it, a bell gets people’s attention.
If something rings a bell, your attention focuses on the memory.
Examples in context:
Let’s look at an example in a real life situation.
Jung Min: Do you know Kim Nam Joon?
Min Hee: That name doesn’t ring a bell. (Meaning: That name doesn’t sound familiar.)
Jung Min: He goes by RM.
Min Hee: Oh! You mean Rap Monster? Of course! He’s a member of BTS!
Jung Min: Yes, him! Have you heard their song Let Go?
Min Hee: Yes, I have it in my iTunes playlist.
Jung Min: Cool.
Min Hee: Speaking of music, have you heard about the Korean high school girl who sang Hello on the Ellen Show?
Jung Min: That rings a bell…when was it?
Min Hee: Hmm…I think it was 2 or 3 years ago.
Jung Min: Right…what was her name again?
Min Hee: Lydia something or other.
Jung Min: Yes! I remember now! Lydia Lee. She has an amazing voice!
Min Hee: Doesn’t she?! She has a single out called Blue. Have you heard it?
Jung Min: No. Is it any good?
Min Hee: I think so, but judge for yourself: Blue.
Jung Min: I love it! I’m adding it to my iTunes playlist.
Here are 10 more English phrases for remembering, reminding, and forgetting by my affiliate Shayna at Espresso English. Oh, wait, make that 9 as it doesn’t ring a bell is included in her list as well!
Never stop learning,
~ Trey