If something is educational, it teaches you some new information or gives you new knowledge. Listening to an organic farmer describe the process of beekeeping can be very educational.
The adjective educational describes something that imparts new skills or knowledge. Reading a recipe is educational, if it teaches you how to make a perfect buttercream frosting for your cake, and a French class is also educational, as long as you learn something new from it. The word comes from the noun education, or "the process of teaching or learning," which actually meant "childrearing" in the 1500s, and was used interchangeably to mean "the training of animals."