Fence off is a term used to describe the act of surrounding, isolating, restricting, enclosing, and excluding an area or object. It is often used to create a physical barrier between two areas or objects, or to keep something out of an area. For example, a fence might be used to fence off a garden from the rest of the yard, or to keep animals out of a certain area. Fence off can also be used to describe the act of keeping someone or something out of an area, such as excluding someone from a group or restricting access to a certain area.