A family of Microsoft word processing software products for creating web, email, and print documents.
Go to File>Options>Display and uncheck the boxes under "Always show these formatting marks on the screen".
Maybe you used CTRL+* on the numeric keypad. The keyboard sequence for toggling the display of non-printing characters is CTRL+SHIFT+8 where 8 is the key above the U and I keys on a US QWERTY keyboard.