There will be 30 half-hour episodes, with more to come. They take place between movies II and III in the life of Anakin Skywalker and will include many of the characters we're familiar with - like Yoda and Obi-Wan and Count Dooku - but also new characters like Asohka. (She's a teenage Jedi-in-training.)
The animated series will be using CGI rather than standard 2-D animation as was the case with 'Star Wars: Clone Wars' (which is available in a 2 DVD set).
'Star Wars' exists in Toobworld, both on Earth Prime-Time (thanks to 'The Muppet Show', many commercials and PSAs, and infamously, to the 1977 holiday special) and in the Tooniverse (the aforementioned 'Clone Wars', 'Droids', 'Ewoks', and also to that same holiday special). This new addition to the lore will be in the Tooniverse as well, although one might assume it will portray events played out in Toobworld in a galaxy far, far away......