The term steal in the poker vocabulary describes a raise made with an attempt to win the blinds without going to the flop.
Players usually do a steal in a late position, i.e., the cutoff or the button, since they don’t have to get through many players to win the blinds.
Given this situation, they can raise and try to steal with a wide range of hands, especially when on the button, since they do not need to hit anything to win. Players in the blinds have two random hands, and often, they simply can’t continue.
Of course, more experienced players are aware that late-position players will attempt to steal the blinds with all sorts of hands and will thus defend and playback at them even with weaker holdings, so they won’t be dead money to you.
