When your grandma says she's "putting her face on" in the morning, what she means is that she's swiping lipstick on her mouth and dabbing plenty of rouge on her cheeks.
Rouge is any kind of red or reddish-colored makeup that's used for tinting a person's cheeks. The word rouge can also refer to the red color itself, or it can be a verb, which you'd use to say, "Grandma, you're uneven — you forgot to rouge your left cheek." The root of rouge is the Latin word rubeus, which itself means "red". A common mistake is to confuse the words rouge and rogue, which means a scoundrel.