l know certain exercises do this and that, but l was told that there are a few exercises that are mass builders. Which ones are those?

Weight lifting with low repetition but high weight amounts will build the muscle bulk faster than a lower weight with more repetitions. That principle is used to tone existing muscles without bulking up. If your interested in building mass, do the first.

Squats.

Start with a moderate weight. Increase a little bit, e.g. 5 lbs each workout. Progress over time so u keep challenging yourself. Put high effort into squats & they will pay off for you, just like they have for generations of others.

Pick other compound exercises (those that use more than one joint r best for development. Such as:

Overhead press
Pull-ups
Bench press
Bent-rows
Squats
straight leg dead lift http://exrx.net/WeightExercises/ErectorSpinae/BBStraightLegDeadlift.html