Elimination is a game mode in which players play in rounds against eachother. Each time a player dies, they will remain dead for the rest of the round, then respawn once the next round begins.
Most competitive matches (also known as Clan Wars) are played in this game mode. Team Deathmatch (known as TDM) is sometimes chosen over Elimination. Elimination is good for competitive play, because lack of respawns incentivize teamwork and punish uncoordinated players. Tactics and callouts are used to help other team-mates out for knowing where enemy players are, or to hold a defensive position on a map.