Could someone please explain the concept of 'credits'?

Hi, I am a student applying from the UK and I am currently on a gap year having finished my a-levels in 2014.
I looked on some of the university websites and saw that they gave “credits” if you received a certain grade or above in your A-levels, and I was wondering what role these ‘credits’ play in your uni application (if any?)

thanks!

see your other post
http://talk.collegeconfidential.com/college-admissions/1771335-could-someone-please-explain-the-concept-of-credits.html#latest