What does it mean to sit empty with a full face?

It means that there is a backer behind the house and an open front.

In geomantic omen, the rise and fall of a house will be judged according to the surrounding mountains. If the house is built empty and full, it will lose its luck and turn Jiwu into a haunted house. Sitting empty and facing the whole sitting is also called sitting backwards. The house at home is built in a gas station halfway up the mountain, and the direction of the house is facing the direction of the mountain. The feng shui pattern will be good, you can get the atmosphere of the mountain, and you can widen the house at the gas stop.