Hilt is the part that goes in your hand. The guard keeps you from cutting off your fingers when you stab rather than slash.
You can call them quillions if you want.
The hilt is everything that isn’t the blade and consists of the grip (the part you wrap your hand around), the pommel (the generally enlarged base that keeps your hand from slipping off the bottom end), the quillon (the cross piece that keeps the hand from moving forward onto the blade), and on some swords and sabers, the knuckle or “D” guard.