What does mean ref_count?

Hi, I have local db and I cen’t figure out what exactly mean ref_count column in table artist_credit?
Also, columnt ref_count present in table tag.

ref_count is generally short for reference_count, so the number of times that entity is referenced (which in MB context would be “used in a relationship”).
I suppose it’s a quick cheap way of determining how many relationship the entity is in, without doing a much more expensive query on other tables.