A webhook is a way of communicating information between two apps, see this great Zapier blog post about webhooks. This allows for experiences like: when someone changes a value in a spreadsheet, it can ping a chat room in another chat app. They work like this:
So to use the bot webhook action, you need to first create the webhook in the app you’re trying to communicate with, and then copy the url into the bot webhook configuration. Then you set up the format as required by the receiving app, and specify the data you want to send along!
Configuring a webhook bot action:
Example action to send a Chat notification:
Example configuration and received webhook ping on the Google Chat app: