Can my mac change a PDF file to a document that I can change?

As Viking OSX suggested, if you have Microsoft Word installed on your MacBook Pro then that is the simplest way to convert a PDF to docx or some other format. But, if you do not have Office on your computer and don't want to spend big bucks to get it there is another--free way--to accomplish this. If you have a gmail account you can upload the PDF to Google Drive; it will open in Drive as a PDF; then at the top of the PDF click "open with" and select Google Docs; after the file is converted to Google Docs format you can then download the file to your computer as a Word Doc or Plain Text file, or RTF or whatever, make changes using Pages or most any other word processing app and then export back to PDF if that is what you need to do.

The other approach that I forgot (again) to mention…

Using Preview you can mark up a pdf, but not edit it. There are 3rd party PDF converters, but most don’t work very well. Edit the source document, if you don’t have it then request it from whoever sent you the pdf. If they won’t provide it, there’s a reason they sent the pdf in the first place.

If you have MS Word v16.31 or later, you can open the PDF in Word, and convert to a Word .docx document. I don't use Word, so don't know what the Word document would look like after the conversion. Probably would allow you to change the preferred text in Word, and then save as PDF again.