Electives are classes that you get to pick to take that may or may not have anything to do with your major. Some majors may require you to take a certain number of elective classes within your college and some that are from another college. Electives are classes that you are free to choose from, that do not fall under the core requirements for your major or under the general core requirements.
Electives are considered as part of your GPA. Some students take certain electives that they know they can pass simply to boost their GPA.