If your TV is broadcasting what you're doing, you may have accidentally turned on the voice guide. The Voice Guide for Vizio TVs is an accessibility feature that can help users with vision impairments. This feature is very sweet, isn't it?
But in general, we don't need VIZIO TV keep talking. If you want to turn off the voice guide, you can follow the path below:
Home > Settings > General > Accessibility > Talk Back >Off