I am confused on what the rover number is, where do I find this?

Your Rover number changes with each client. The Rover number you see in the message is that client's Rover Number. They can see your Rover number when they look at the conversation online or if they receive text notifications. You don't ever see your Rover Number since it changes with each client.

If you mean Rover's Customer Service phone number, it is [Edit: Rover’s contact options have changed. Visit the Rover Help Center at https://support.rover.com/ to find the phone number, help articles, or chat with the team] and can be found at the bottom of his page as well as others.

If you mean your Rover phone number, it appears within conversations/bookings you are having with customers. Go to your inbox, select the stay message from the customer you wish to give the number. You will see it right below the info/pic of the dog.