黑料不打烊

The definition I can find

You need so many credit hours in a subject for the class to count for graduation and a lot of schools bill by credit hour

Credit hours are a way of measuring how much credit a student receives for taking a class. The credit hours correspond to how many hours a week you meet for the class. Most college classes require you to only meet two or three times a week - although some classes also only meet once a week (but for much longer). Let's say you had a class that met for one hour on Mondays, Wednesdays, and Fridays, a pretty common scenario in college. In that example, the class would be worth 3 credit hours. You could have a class that meets on Tuesdays and Thursdays for 90 minutes, that class would also be 3 credit hours.

I would say that credit hours don't really influence majors and minors too much. Most colleges require you to hit a minimum number of credit hours before you can graduate. Typically I think it's around 120 credit hours for a college using semesters and closer to 180 hours if they have quarters instead of semesters. Does that help answer your question?