The word "slay" primarily means to kill someone or something in a violent or brutal manner. It can also be used in a more informal context to express doing something exceptionally well, often used when someone impressively showcases their talents or skills.
The word "slay" comes from Old English "slēan," which means "to strike, kill, or slay." Its roots can be traced back to the Proto-Germanic *slāhaną, which is related to similar words in other Germanic languages.