決定 (けってい) is generally a selectable icon on the screen or the action of one of the buttons on a video game controller. You use it to lock in settings or confirm selections, so it can be translated as “confirm” or “enter” depending on context. This is definitely a word that I’ve seen far more often since starting this job. I’m sure it gets used out in the real world (probably more along the lines of “come to a decision”), but I don’t think I ever had the opportunity to use it personally.