When you want to deploy your Laravel app to a live environment, you want to make sure no one can see any debug message as this may contain information about your application that you do not want to spread.
First off, make sure your APP_DEBUG is set to false inside your .env file. Also change the APP_ENV from local to production. This makes sure your user wont be able to read any debug messages when a error is thrown.
If you're using third party packages to debug your application make sure you disable them, or only make them available for yourself (by checking IP or what ever).
For example if you're using the Debugbar package make sure you mark DEBUGBAR_ENABLED to false so the bar will not show itself.