An atom has no overall electric charge, so we say it is electrically neutral. This is because the number of protons is always equal to the number of electrons in an atom.
Each proton has a relative charge of +1 and each electron has a relative charge of -1. When the numbers are equal, the positive and negative charges cancel and the total charge is zero. Neutrons have no charge, so they do not affect the total.
For example, a fluorine atom has 9 protons, so it must have 9 electrons. If the numbers were not equal, the particle would have an overall charge and would not be a neutral atom.