The Review Ribbon
The REVIEW ribbon is used for reviewing Ah! ah! you would not have guessed.... seriously, it used for proofing your text, setting the language, inserting comment for other people to see and locking certain area you want not to be seens (for exemple secret formulas).
Here a quick overview.
The Proofing area allows you to start the spelling check (you can start it with F7 also). Do research on words and check the Thesaurus if you are unsure about your words.
The Language area allows you translate any word or sentence in any language. Quite useful.
The Comments area allows you enter comments into a document for yourself or others to read and comment over.
The Changes area allows you protect the spreadsheet or the workbook (all the sheets). You are totally free to protect anything you want as you can see in the window.