face without makeup; unpainted face
Refers to a person's natural face without makeup or cosmetic covering. Common in everyday and media language.
I went out without makeup today.
She looks beautiful even without makeup.
true face; real nature; true picture
Figurative use for what someone or something is really like behind a public image, official face, or superficial impression.
The interview revealed the actor's real self.
This program shows the true face of regional cities.
Rare use referring to a face or state not affected by alcohol. In modern Japanese, 素面（しらふ） is the ordinary word for being sober.
In an older usage, 素顔 can refer to a face showing no signs of drunkenness.
She only shows her true self to her closest friend.
On my days off, I go shopping with no makeup on.
This program is a documentary that gets close to revealing celebrities' true selves.
素顔 means a bare, unmade-up face, the direct opposite of wearing 化粧.