How can I edit words on a document or resume

Your ability to edit your Resume, as with any document, would be heavily influenced by the document format.

The free Apple Pages App is able to open and edit many (but not all) document formats. There are many Apps that you can download that are designed to work with PDF documents - these Apps having differing capabilities and complexity.

If your Resume was created using Microsoft Word on a PC or Mac, there is an equivalent Microsoft Word App for iPad.

All the available Apps can be found within - and downloaded from - the Apple App Store.