If you open a Word document and see what looks like large Ps at the end of every sentence, then the Show/Hide marker has been turned on.
Sometimes this gets turned on by accident or when you open a doc which as these turned on by default.
The the Show/Hide marker is used for examining the document’s formatting as it shows details of the underlying paragraphs, section breaks and page breaks.
You can turn off this by clicking the paragraph marker. This is usually located on the toolbar.
Related: Microsoft Word Tips