how do I turn my camera on and off on my Mac air

There are applications whose activation should turn 'off -or- on' built-in camera.

..Some macOS versions within latest hardware may control camera differently..

• Turn the camera on:

On your Mac, open an app that can use the camera, such as FaceTime, Messages, or

Photo Booth. A green light beside the camera glows to indicate that the camera is on.

• Turn the camera off:

On your Mac, close or quit all apps that can use the camera. The green light beside the

camera turns off, showing that the camera is off.

• macOS User Guide - [Table of Contents] Apple Support

//support.apple.com/guide/mac-help/toc/11.0

For instructions, those vary a little; built-in cameras can be within Displays, too.

..Also there are user-guides within the macOS of most Apple computers. Some

are hidden some through "About this Mac" & dig, under Finder menu selections.

• Use the built-in camera on Mac - Apple Support

"The camera automatically turns on when you open an app—such as FaceTime or Photo Booth—or use a feature—such as Markup or head pointer—that can use the camera. A green light beside the camera glows

to indicate the camera is on. The camera (& the green light) turn off when you close or quit all apps or

features that can use the camera."

//support.apple.com/guide/mac-help/use-the-built-in-camera-mchlp2980/mac

"..To learn more about using your camera with the apps mentioned, see

FaceTime User Guide, Messages User Guide, and Photo Booth User Guide."

+ Control access to your camera on Mac - Apple Support