Hola VPN turns any device it is run on in an exit node which anyone may purchase access to.
Hola uses a sophisticated system to offer its services for free. Instead of routing users solely (or at all) through company servers and raking up huge bandwidth bills in the process, it is utilizing user devices as endpoints.
This means basically that any user device that Hola is running on acts as an endpoint. An endpoint is a node that is communicating directly with a target website or service that Hola users access when the service is enabled.
I've read a few articles about this in swedish but here is one in english. English article: http://www.ghacks.net/2015/05/28/beware-hola-vpn-turns-your-pc-into-an-exit-node-and-sells-your-traffic/
If you are a Hola user, make sure you are protected.