You can think of a 'workshop token' as a virtual currency which can be spent within the app. Normally, one workshop token can be exchanged for one free workshop, which will be added to your library and which you'll get lifetime access to!
It's easy - once you've found something you'd like to learn, just use a token to add it to your library and get learning.
If you'd like to find out more about how to earn free workshop tokens then you can read more here.