The sentence you wrote is grammatically correct! Let's look at it step by step:
- The bear cub is the subject. It tells us who we are talking about.
- watches and learns are the actions the bear cub is doing.
- from its mum tells us who the bear cub is learning from.
- wherever she goes means 'in every place the mum goes.'
Everything fits together nicely, and the sentence makes sense. Good job!