What does a card with First strike do in Magic The Gathering?

Answer 1

'First Strike' means the creature deals combat damage before others. That can mean it may be able to kill an attacking or defending creature and not take any damage in return.

For example if a 2/2 attacks and is blocked by a 2/2, and defender is granted First Strike, it will deal this damage first before other monsters. This damage will kill the attacking monster before it can deal damage back to the defender.