By default, items on order flows show the price underneath (e.g. registration types, add-ons, activities, etc.):
If you have events that are entirely free (no paid registration types, activities, or add-ons - 100% free), then you may not want "Free" to show under each item.
To hide the pricing information, go to the Advanced Options of your event (Select Event > Edit Event > Advanced Options), then select the 'Hide pricing information' checkbox.
With "Hide pricing information" enabled, registrants will not see the word "Free" under items on the order flow.