Here's how to break down the formula:

* Na₃: This represents three sodium ions (Na+)

* Al: This represents one aluminum ion (Al³+)

* PO₄: This represents one phosphate ion (PO₄³-)

The charges of the ions must balance out to create a neutral compound. The three sodium ions have a total positive charge of +3, and the phosphate ion has a -3 charge. This balances perfectly with the +3 charge from the aluminum ion.