To change any of the text labels on the booking form go to Dashboard > Translations > English.

Type in the text you want to change in the Search bar and click on the Search icon.
Click on the text in the right hand side Translation column and you will be able to edit it.
After you are done editing click on Save & Close.

Go to the front end to make sure that your changes have taken effect.

You can use this feature for any language other than English. 
Edit the booking form text to fit your business.