Skew refers to the angle of the LNB relative to the rest of the dish, you are maximising the gain of the LNB.

This could be the difference between a good watchable picture or poor reception.

All geostationary satellites are located above the equator (the Clark Belt).

They are placed here to match the rotation of the earth. Inside a satellite’s footprint, LNB skew is not all that important, however as you approach the fringes of the signal footprint it becomes ever more crucial to getting good reception.

The LNB is kept in place by either a screw or a nut.