The bouncer has two sides.
The baby side is designed for use by newborns, until they can sit unaided. The baby side is designed for tiny babies and has a safety harness that should always be buttoned up. The safety harness has two different sets of buttons so that you can adjust the size to fit your baby.
Once your child can walk and sit unaided, turn the fabric around and use the chair side. The bouncer can then be used as a chair for your child. The safety harness cannot be fastened when using the chair side as, by this stage, your child will no longer need restraining.