Yes! You can always add a customized message to the email confirmation a customer receives. You can do it two ways:
1- Go to Listings > Activities and click into the activity, click on more details and add specific email notes for the specific activity.
2- Click into the profile button on the top right, click into Business Setup and then add your customized message in Extra Notes for Order Confirmation. The language you add here will be on ALL confirmations across the board vs. activity specific.