How to correct spelling mistakes by using Word's suggestions

When a word is spelled wrong, it gets marked with a red underline (meaning it doesn’t appear in the built-in dictionary).

A common spelling mistake happens also when you accidently omit the space between two words, it will be considered by Word as a "typo", and marked with red underline.

When you right-click such a word, you will usually get a list of suggested corrections (if it has any).

If you find the correct spelling among the list, then click it and it will replace the misspelled word.