TRX are the tokens for another blockchain, deeper down the rabbit hole.
( or further out depending on how you think ^_~ )

It is often equated to ethereum, for being a kind of a decentralized operating system hosting and processing smart contracts and attempting a branching ecosystem of decentralized applications which share the same chain.

However, the most simple answer is that it is another form of cryptocurrency which you may eventually trade/sell supposing it lacks any utility for whatever you're doing at the time. In the last 24 hours, TRX has had about $850,000,000 in trading volume on listed exchanges alone.