Discover is a feed that appears on the home page of Google's iOS and Android app, as well as the mobile Google.com homepage. Users can personalize their feeds so they see content that pertains to them. People do not need to enter a search query to have these ads appear. If you do not need it, you can turn it off.
Setting Path:
Method 1: Turn on Google Chrome > Discover by Google > Setting icon next to Discover > Turn on/off.
Method 2: Open Google App > Tap on Profile on top right > Settings > General > Discover > Disable/enable it.