Mukh Gyani is a term for a person who has gained knowledge, but yet does not follow his/her life according to the knowledge they have gained.
If, for instance, a person knows about Sikhi and has become so familiar with the Guru Granth Sahib that he understands its philosophy and even sings about Guru Nanak's philosphy in public. Daily he shares the teachings of the Granth with his fellow beings, yet in his own life, whether in his home or business, he doesn't follow the Guru's philosophy at all. In the Punjabi language such a person is referred to as a Mukh Gyani.
Punjab, like the rest of the world is full of Mukh Gyanis, people who know better, but continue to live their lives as they always have.
Mukhgyani = Mukh + Gyani
i.e One who is knowledgeable, but does not practice the knowledge he has gained.