In combat, it rolls its own initiative and acts on its own turn. A familiar can’t attack, but it can take other actions as normal.
As an action, you can temporarily dismiss your familiar to a pocket dimension. As an action while it is temporarily dismissed, you can cause it to reappear in any unoccupied space within 30 feet of you.
While your familiar is within 100 feet of you, you can communicate with it telepathically.
Additionally, as an action, you can see through your familiar’s eyes and hear what it hears until the start of your next turn, gaining the benefits of any special senses that the familiar has. During this time, you are deaf and blind with regard to your own senses.
Finally, when you cast a spell with a range of touch, your familiar can deliver the spell as if it had cast the spell. Your familiar must be within 100 feet of you, and it must use its reaction to deliver the spell when you cast it. If the spell requires an attack roll, you use your attack modifier for the roll.