The word slew has two completely unrelated meanings:

1. A large number or amount of something. If your teacher assigns a slew of homework problems, you're looking at a big pile of work. A popular new video game might attract a slew of players on its first day. The word suggests an almost overwhelming quantity. You might say “I have a slew of chores to do this weekend” when your parents have listed what feels like dozens of tasks.
2. The past tense of slay, meaning to kill. In fairy tales and legends, the brave knight slew the dragon threatening the kingdom. You'll see this word often in older stories and historical writing. Today, people rarely use slew this way in everyday conversation, though you might still encounter it when reading classic literature or tales of medieval battles.

These two meanings share nothing but spelling. When you see slew in a sentence, the context will make it clear which meaning applies.