There's also a large variety of equipment that you can use for resistance training at home, like resistance bands, weighted bars, ankle weights, and dumbbells etc. Nelie has her own kettlebells at home!
An exercise is considered to be muscle building IF you take the muscle to fatigue or exhaustion within 60 - 90 seconds. So long endurance exercises (like cardio) won't build muscle but you certainly can build muscle with bodyweight exercises if they're challenging enough.