At some airports, in addition to (or in place of) lounge access, your Priority Pass membership gets you a dining credit at select restaurants. There are currently more than two dozen of these restaurants in US airports, and another dozen internationally. The Points Guy has a comprehensive list.
At most restaurants, the credit is $28, while at a few it’s $30. The credit is per person, so if your Priority Pass membership allows for guests, you each get the credit. However, you cannot use multiple credits for yourself. The credit is also per restaurants, so for airports with multiple restaurants in the program, you could visit multiple in one day.
Typically you’ll need to show a boarding pass for confirmed same day travel; some restaurants require an outbound boarding pass, while others allow you to use the credit upon arrival. If you go over the $28 amount, you’ll simply need to pay the difference. And don’t forget to tip your server as the Priority Pass credit can’t be used for gratuity.