The player's goal in Valorant is to detonate/defuse the spike (an explosive) or kill the entire enemy team.
Once you launch the game, you'll either start as the defending or the attacking team. If you're an attacker, your goal is to put down the defenders or plant/detonate the spike.
On the other hand, if you continue as a defender, you need to take out the attackers. If they plant the spike, you have to defuse the planted spike to win the round.