Cannot print a PDF document emailed to me

The author of the document has the ability to prevent printing or copying of the document. If that’s the case, you’re going to have to get an unrestricted copy from whoever sent it to you if you want to print it.

Right-click on the PDF attached to the email and choose Open With > Preview which will open the PDF. If you know that your printer is otherwise working correctly and the PDF will not print from Preview, press cmd+i to open the PDF inspector. On that inspector toolbar, you will see a lock icon. Click that to see the PDF-specific user permissions.

If those permissions are all green, then the PDF author did not restrict the printing of the PDF and there is another (as yet) undetermined reason. If the print permission is not green follow KiltedTim's advice about having a printable version resent to you.

Do a screenshot(s), open the image file(s), left click and drag to highlight the text, Command-C to copy, then paste into a text editor and print from there. It's fiddly but does the job if all else fails. If the screenshot is acceptable you can print the image.