Fitness

i know this might sound dumb..but what is a rep?
like a repitition?

for example, 1 set of 12 reps? i dont get it =/

It's not dumb.. i didn't know when i first started either.

A rep is the number of "repetition's" to do of the same exercise, so say your doing squats and you squat down 6 times that's 6 reps. 

Sets refer to the number of times you do that ... so if you do 6 squats then take a little break (a minute of two) and then do another 6.

You've done 2 sets of 6 reps.  

Hope that makes it clearer.