fence off
To create a barrier so that someone or an animal can't access something else. A noun or pronoun can be used between "fence" and "off." I fenced off my vegetables, and yet, it looks like our friendly, neighborhood deer population is still snacking on them regularly. We need to fence the pool off so the kids can't get to it on their own.
fence someone or something off (from something)
to separate someone or something from something else with a fence or barrier. We fenced the children's play area off from the rest of the yard. Dave fenced off the play area. We fenced off the children from the rest of the yard.