Taming Beasts, or Beast Control, was an ability of the Force to mentally connect with a wild animal. The ability required the user to let go of their self-consciousness, lower their guard and open themselves up to the power of the Force.
Kanan demonstrated this to Ezra by taming a Loth-cat, and later helped him to tame a pack of fyrnocks. When Ezra brushed against the Dark Side, it enabled him to summon a monstrously large fyrnock to attack the Inquisitor. Although it left him drained and feeling cold.
Ezra has shown an affinity for this power time and again such as when he used this power to persuade a Loth-cat to attack a probe droid, rally a pod of purrgils, and call a tibidee to carry him and Kanan to safety.
However, as Ezra discovered, it is not always possible to connect with creatures, as he discovered when he struggled to connect with the Krykna Spiders. However, the Bendu taught Kanan Jarrus to "see" the spiders through the Force and relate to them, which helped Kanan pacify the creatures to not attack him.