Allows you to outline the text segments in your selection.
This means you turn the text characters into a set of compound paths. In other words, your text will no longer be a true font, but it will be replaced with a graphical representation of the characters. You can then for example change the fill or stroke color as required.
This can be useful to make sure that your text is printed exactly "as is" or, if you cannot embed the font, for example due to font licensing restrictions.