"Full Pay" means at least 100% pay back.
The exception is 9/6 Jacks or Better, it's 99.54%.

Every video poker machine has a pay table.
By playing perfect Basic Strategy your rate of return will be according to the pay table.

This Wynn 9/6 Jacks or Better machine is identified by looking at the numbers for Full House & Flush (red arrows):

Full House is 9 and Flush is 6, which means it's a "Full Pay" machine.
If the numbers are lower your rate of return will be lower, at an advantage to the casino.

By checking the type of game and pay table you identify if it's a "Full Pay" machine.