If you are looking for a way to make simple edits to a PDF document, such as adding a signature or some additional text/terms to an agreement or contact, Microsoft OneNote is a good option.
It is part of Microsoft Office Home and Student edition, as well as the Ultimate edition. It can also be purchased individually. If you don’t already have Microsoft Office, there are cheaper alternatives out there. But if you do, to edit a PDF all you need to do is open your PDF document and then select Print, and Print it to a OneNote file. The new document will automatically load on your computer, where you can then proceed to make changes and save the document as a new PDF file. This is just one of many ways to edit a PDF document, but a very simple one if you already have OneNote installed.