As Beth says! However the content will deal surely with a practical theme, the practical part of what has been previously studied.It will of course depend on the subject to define this term accurately here.

o.k got it! Practical notebook here is talking about a practical theme I think. She is always writing such stupid things on italki, she never writes practical notebooks, how can she think that will help her in China? It could also possibly mean like Cherry said, to write about practical work already studied in a class for exam. However my gut tells me it's talking about a writing of a practical nature!

Out of context it is almost impossible to give you an answer to this. It could be a physical notebook that is practical, it could refer to writing a notebook on here about a more practical subject, there is so many things it could be. Can you please give us the rest of the sentence then we can give you a proper reply!