Planet Zoo is a game about taking care of wild animals. You must build the zoo, take care of the animals, and make sure the zoo brings in enough money to maintain itself. You start out with a small area of land and you must build your zoo's infrastructure.
You must hire staff and purchase animals to be placed in your zoo. You can also hire staff to take care of your animals and make sure they are healthy.
There are some animals that need special care, such as the giraffe that needs a platform built for it to stand on. You can feed the animals, take them to the bathroom, and bring in guests to see them.