Hi.I want to know what does 10+2 mean. I have done diploma after 10th so i want to ask can i give exam of 12th science?

dear 10+2 means higher secondary in school, dat means a second year class after 10th. after 10th student opt for some stream like medical, non medical, commerce or arts. then he/she get promoted to 11th class which is called as 10+1 and after clearing 11th he /she get promotion in 12th class dat is