So I have been going to this saturday school to learn spanish since I was 4 ( I am 16 now) and I get a diploma when I graduate next year. Do colleges like that or would they just ignore it.
I think that’s a wonderful EC! It shows a commitment to sticking with something. Yes, colleges will like it and good for you!
Yes, long term commitment to developing a valuable skill is appealing to a college admissions committee.
Yes, do include it! If your Saturday teachers are getting you ready for the AP exams, think seriously about taking them. If the SAT II Spanish subject test and/or the CLEP Spanish test would be useful for credit, placement, or exemption from a foreign language requirement at your college(s), think about taking those exams. Happykid attended a Spanish Saturday school from 3rd grade through 10th grade, and earned 12 semester hours of college credit for her score on the CLEP Spanish test. 
Cheapest credits ever!
¡Felicidades! That type of effort reflects more than the acquisition of a useful added language. It demonstrates an incredible commitment outside of a regular school day and is an achievement that won’t be lost on a college.