Fetching details from the dictionary...

face; official stance; public position or attitude (as opposed to private thoughts)
ceremony for the erection of the framework of a house
本音と建前を使い分けるのは日本文化の特徴だ。
Distinguishing between true feelings and public stance is a feature of Japanese culture.
建前では賛成していたが内心は反対だったようだ。
He was in favor on the surface, but it seems he was opposed inside.
会議では建前ばかりで本質的な議論が進まない。
In meetings, only lip service is paid and substantive discussion does not advance.