A "stamina meter" refers to a visual representation or measure of how much energy or endurance a character in a game or a person in real life has left to perform actions or activities before needing to rest or recharge. Full definition
Just like you the AI enemies all have a visible stamina meter under their health that you can use to your advantage, just like they can do to you. (ludophilelab.com)
Then I noticed I could climb down the hole slowly (but not too slowly, because stamina meter). (thatvideogameblog.com)
There is also a new stamina meter this year also. (gamingnexus.com)