The main function is learning to produce vocabulary in the context of a sentence.
So mostly vocabulary, and maybe a little bit of reading practice. There are also “challenges” for reading and listening for some courses, but they haven’t been released for English->German yet so I can’t really tell you anything about them.
It’s good for what it does, but you’ll need to do other things to practice grammar and speaking. I find youtube videos are good for learning grammar, and duolingo is good for practicing what you learned. For speaking, you should probably find a native speaker to practice with