You have received an email which has an attachment, but the document won't open, or appears to be gibberish. This is because your computer or device does not recognise the document type.
Please save the document to your desktop (or somewhere you can easily find it again). Then run Adobe (Acrobat) Reader and use File/Open to open the document.
You need to open the file with the right app/software sometimes simply tapping or double clicking the document does not work.