What does it mean when a chemical equation is balanced?

Answer 1

A balanced equation will have the same number of each element on both sides. Additionally, the energy lost on one side will equal the energy gained on the other.

For example: 2H2O = 2H2 + O2

Answer 2

A balanced chemical equation has the same number of each type of atom on both the reactant and product sides. This ensures that the law of conservation of matter is upheld, meaning that no atoms are created or destroyed during a chemical reaction.