To face up to something is to accept a difficult truth and deal with it. Face up to the debt, face up to what happened.
It implies the truth was being avoided, which is what the up adds. It is used of facts about oneself more often than about the world.
1phraseface up toTo accept a difficult truth and deal with it.
“He had to face up to the fact that the business was finished.”
face up to is a phrase.
Practised in Phrasal Verbs