Foil balloons are sold uninflated. Most florists/party stores/ grocery stores will fill with helium for a small fee. Foil balloons can also be filled with air. If you choose to do so, you can insert a straw in the valve of the balloon and blow into that or you can use a balloon pump or balloon inflater.
CHOKING HAZARD – Children under 8 yrs. can choke or suffocate on uninflated or broken balloons. Adult supervision required. Keep uninflated balloons from children. Discard broken balloons at once.