To make the water stop flowing from a faucet, you "turn it off". Use "turn off" instead of other words like "shut", "stop", or "close".
You also "turn off" these things:
- the lights
- the TV
- the heat
- the oven
- your (cell) phone
- the engine (of a car)
"Turn off" is a phrasal verb. Like a lot of phrasal verbs, the object can come afterward like this:
Turn off the faucet.
And it can also come between "turn" and "off":
Turn the faucet off.
But "it", "them", and "that" have to come in the middle. They sound weird at the end:
Turn it off.