DId a quick Google search.
Yes, Coinhub is an exchange; and it's a small one. It looks to be working fine, but I don't know about the security and customer support.
Any reason you're interested in Coinhub? As they only currently trade very very few coins(BTC, ETH, LTC, DASH, DRG, and BBI). I'd personally go with Binance instead[1].
[1]
https://binance.com/