A familiar face; someone you see often enough to recognize (an acquaintance).
駅前のパン屋にはいつも顔なじみのお客さんがいる。
There are always familiar customers at the bakery in front of the station.
彼は飲み屋で顔なじみの店員と長話をしていた。
He was chatting at length with a familiar clerk at the bar.
顔なじみの人に会うと安心する。
I feel reassured when I run into someone familiar.