The Ubound() function returns the highest number of your array. For example, If I had this code:

Code:
Option Base 1

Dim MyArray() as Integer

Private Sub Form_Load()
   Redim MyArray(15)

   MsgBox "Ubound returns " & ubound(myarray) & ". Lbound returns " & lbound(myarray) & "."

   Msgbox "Ubound should return 15 while lbound will return 1 (option base 1)."
End Sub