It depends on the article. Some articles are available in PDF format and you can save a copy. In OneSearch, you should be able to see a link for PDF or maybe to another source that likely has a PDF version of the article. If you've clicked the link for full text but don't see PDF anywhere, that may mean that it's not available in that format.
If the article is not available in PDF, you could copy and paste the text into a MS Word document and then print to or save as a PDF (all library computers have this capability and your personal computer might as well). Additionally, some articles will be available only in HTML (text only), which you could save.*
*Caution: If your professor specifically said to get an article in PDF, creating one out of an HTML text article or saving the available HTML text might not be what they want. In that case, you would need to find another article that is available in PDF.
