Do you mean the Activity title?
You can detect the Language with this code:
B4X:
Sub Activity_Create(FirstTime As Boolean)
Log(GetDefaultLanguage)
End Sub
Sub GetDefaultLanguage As String
Dim r As Reflector
r.Target = r.RunStaticMethod("java.util.Locale", "getDefault", Null, Null)
Return r.RunMethod("getLanguagee")
End Sub
You will need the Relfection library. You can detect the language and so put whatever you want in the Label