Welcome to the forums,
I assume you're talking about an HTML REST view of a public cal embedded in a webpage such that you can't tell just by the page title or from the Url: server.domain.com/zimbra/home/username/Calendar.html (ie: are you pulling it so dynamically that you can't display a title next to it?)
The names is listed in the bottom left where you can click to get an .ics:
You could open an RFE in
bugzilla if you'd like to ask that the calendar name be displayed elsewhere.
Bugzilla
Wiki
Source
Add calendar name to public calendar view 
Linear Mode
