Assuming you are referring to a typical sink faucet, it is operated by two handles, each with its own function. The left handle controls the hot water while the right handle controls the cold water.
To turn the water on, you simply need to lift up on the handles. The further you lift the handles, the higher the water pressure will be. To adjust the temperature, you will need to use both handles at the same time. The further you turn the hot water handle to the right, the hotter the water will be. The further you turn the cold water handle to the left, the colder the water will be.
To turn the water off, you simply need to push the handles back down into their original position. It is important to note that you should always turn the water off at the handles before you leave the sink area. This will help prevent any accidental water usage and potential flooding.