When a player puts a bounty on someone's head, that means that whoever beats the guy holding the bounty will get the TC placed.
There are also bounty texts, those cost 2k (the person who puts the bounty on the other's head has to pay the bounty prize and the 2k for the text). If you claim the bounty, the bounty text will show up below the person's name when they play ingame.
And when someone places a bounty on you, you will get a PM telling you so ;)
Hope this helps.