Its means belonging to it. You use it for a thing, an animal, or a baby whose sex you are not naming.
The dog wagged its tail. The tail belongs to that dog. Or: The car lost its wheel. The wheel belongs to that car.
Its means belonging to it. You use it for a thing or an animal. The dog wagged its tail. The tail belongs to that dog.
The house has its own garden. The garden belongs to that house.