Check spelling, grammar, and clarity In Word
Word autocorrects a lot of mistakes for you, and if it's not autocorrected, you'll see colored underlines appear under words to check for spelling, grammar, and clarity.
To check each item that Word finds, right-click the underlined text and learn more about the issue. Accept the change that Word suggests, or ignore it.
To check the whole document, moving to each issue Word finds, press F7.
Source: Microsoft