The Claymore is a directional mine. When deployed it has two orange lines indicating the area of effect. Any enemy player who enters this area will detonate the mine. These weapons deal a flat 700 damage. When detonated, Claymores will destroy any other mines in their area of effect, so be careful when placing them. Once deployed an icon will appear in the bottom left of the player's HUD until the mine is destroyed.
A single Claymore is not enough to deal with a light class at full health. However, they are a great help if you damaged the incoming capper beforehand with your sniper rifle or makes at least the chasing easier.
When fully upgraded, you start with three Claymores to deploy and can deploy three at a time. Keep in mind though, that Claymores on the flag stand are very easy to see for incoming cappers, who can clear them with a single hit before going for the flag, so you may rather want to use them in more hidden locations to surprise the enemy.