Nameberry only lists [name]Halle[/name] as a diminutive of [name]Harold[/name], but other sites claim her meaning as “Heroine”.
I consider nameberry a trusted source… Are the other sites wrong?
I consider Behindthename.com my most trusted name site for factual meaings and etymology. They say:
[name]Halle[/name] – [name]Male[/name] – Norse – From the Old Norse name [name]Halli[/name], a diminutive of names containing the element hallr meaning “rock”.
And from their site it says [name]Halle[/name] [name]Barry[/name] (spelled wrong there) was named for a department store.
[name]Halle[/name] is originally a Norse boys name meaning ‘rock’. I like it but had to give it up because I struggle to pronounce it the correct way.
Edit:: Haha, yeah. What Dantea said 
All of this. I don’t trust Nameberry’s meanings…
Since in English [name]Halle[/name] is mostly a form of [name]Hallie[/name], which is a nickname, I guess the meaning would depend of what the original full name was.
For example, [name]Hallie[/name] is usually a a diminutive of [name]Harriet[/name] — ultimately from the Germanic name [name]Heinrich[/name], “home+ruler”. If you see it as short of Halldora ("[name]Thor[/name]'s rock") or [name]Halcyon[/name] (“kingfisher bird”) or Haroldine (“army leader”), the meaning would vary accordingly.