A pdf is a very handy type of document, which as you have already seen can be very easily added in your school’s courses

In some learning activities, you might wish to enrich your learners’ knowledge with material that they check on their own time and pace. So, why not let them download or print the shared pdf? On the other hand, if you are going to upload original material made by you, you might prefer to protect it.

Just go to your "Settings" and select "Copyright protection". 

On this page, you can handle your PDF protection by deciding whether your users will be able to download, copy, and print your PDF.

If you select the options of downloading and printing, your students will be able to find the relevant buttons on their course player.

Otherwise, if you prefer to keep your data protected just leave the respective boxes unchecked and these two icons will disappear from your course player ensuring that your pdf file cannot be downloaded and printed. Also, if you are in the Learning Center plan you are able to add a watermark in your PDFs as explained here.

If you want to refresh your memory on how to upload your pdf as a learning activity check this article here.