A more thorough explanation:

An enclosure is a boundary that limits access around a piece of land. It can be a natural or artificial barrier such as a fence, wall, hedge, or ditch. The purpose of an enclosure is to mark the boundaries of a property and prevent others from entering without permission.

For example, a farmer may enclose their land with a fence to keep their livestock from wandering off and to prevent others from using their land without permission. In a legal context, proof of an enclosure is important in a claim of adverse possession. The adverse possessor must show that their enclosure marks the boundaries of their adverse occupancy.

Enclosures can take many forms as long as they are visible and sufficiently denote the location, area, and extent of the land being claimed. For instance, a row of trees or a natural stream can serve as an enclosure if they clearly mark the boundary of a property.

Overall, an enclosure is a physical boundary that defines the limits of a property and protects it from unauthorized use or access.