You have an uncommon way with animals and your bond allows you to train them so they can join you on your adventures. Your animal companion is friendly to you and your companions and obeys your commands. Choose its stat block - Beast of the Land, Beast of the Sea, or Beast of the Sky - which uses your proficiency bonus (PB) in several places. You determine the kind of animal the beast is, choosing a kind appropriate for the stat block.
In combat, your animal companion acts during your turn. It can move and use its reaction on its own, but the only action it takes is the Dodge action, unless you take a bonus action on your turn to command it to take another action. That action can be one in its stat block or some other action. You can also sacrifice one of your attacks when you take the Attack action to command your animal companion to take the Attack action. If you are incapacitated, the beast can take any action of its choice, not just Dodge.
Once your animal companion gains a proficiency bonus equal to 4, you can spend downtime days to train it to make two attacks. You must train for 3 days total, but these days do not need to be consecutive.
If your animal companion dies, you may use downtime to train a new companion. It requires 7 consecutive days of training for a new beast to become your animal companion.