While on a call in Zoom, you may want to turn off your camcorder video and mute the sound from your microphone for a variety of reasons. Here's how you can do this, including some keyboard shortcuts to speed things up.

How to turn off the camera video
To turn off your video on a Zoom call, click the "Stop Video" button in tool bar near the lower left corner of the Zoom call window.
You can also press Alt + V on a computer to turn the camera on or off.

While Zoom is not sending your video to other people, you will see a camera icon with a red vertical. Other people will not be able to see you.

How to mute your microphone
To mute yourself on a Zoom call, move it mouse in the lower left corner of the call window in Zoom and do click on the "Mute" button.
You can also press Alt + M on a computer or press the Space key to mute and unmute yourself.

While Zoom is muted, you will see a microphone icon with a red vertical. Other people will not be able to you listen.

How to turn off the microphone and video
To select whether Zoom automatically turns on your camera and microphone when you join a meeting, you can go to the Zoom settings window.
To find it, click on icon of your profile in the upper right corner of the main Zoom window and click on "Settings".

To turn off automatically the video of the camera when participating in a Zoom call, click on "Video" on the left side of the Settings window.
Check the "Turn off my video when joining a meeting" check box to the right of Meetings.

For automatic mute of its sound microphone When you join a Zoom call, click "Audio" on the left side of the window.
Select the "Mute my microphone when joining a meeting" option.

You can choose to turn on the video and him sound anywhere in the meeting by clicking the buttons or using the appropriate keyboard shortcuts.