Wikipedia is an encyclopedia that's available for everyone for free. This is possible because we edit it in our spare time. We write, we proofread, we patrol recent changes and revert vandalism. We translate.
There's more, of course: Wiktionary, the free dictionary. Wikimedia Commons, a collection of images, videos and sound files anyone can use. Wikisource, a digital library with free texts. More still. Together we form the Wikimedia movement. And all these initiatives depend on information being available in as many languages as possible. You could help us here.
You can join us on the Wikimedia translators' mailing list. It doesn't have a lot of traffic.