The phrase "unlimited ammo" means that you have an infinite supply of bullets or ammunition for a weapon.
Sentences with «unlimited ammo»
I had no idea you could get unlimited ammo for special weapons, though. (segadoes.com)
Though to balance it, they'd probably expand his arsenal overall outside of the episode and just let you equip that stuff with unlimited ammo like anything else. (novacrystallis.com)
There is a glitch in the game that allows the player to carry unlimited ammo. (thetech52.com)