You don't need a kinesiology degree to train well — but knowing which muscles a lift targets, and the handful of terms that describe how they work together, makes every program on this site easier to follow and every exercise choice more deliberate.
A muscle's origin is its fixed attachment point; its insertion is the point that moves when it contracts. Knowing both tells you exactly what a muscle does.
The agonist is the muscle doing the work (biceps during a curl); the antagonist is its opposing muscle that relaxes to allow the movement (triceps, in that example).
The prime mover generates the main force of a lift. Stabilizers don't move much but hold a joint steady so the prime mover can work efficiently — your core during a squat, for example.
Every muscle is a mix of fiber types with different jobs — see the table below for what each type is actually built for.
* Everyone has both fiber types in every muscle — genetics set your baseline ratio, but training biases which type adapts more.
Now that you know what each muscle group does, see exactly how they're trained — rep ranges, exercise tiers, and full program splits.