Hello Try this code
Sub Test() Dim arr As Variant
Dim i As Long
Dim v As String
Dim x As String
Dim y As String
Dim z As String
Dim s As String
arr = Range("B1:B" & Cells(Rows.Count, 2).End(xlUp).Row).Resize(, 2).Value
For i = LBound(arr, 1) To UBound(arr, 1)
If Not IsEmpty(arr(i, 1)) Then
v = Left(arr(i, 1), 3)
x = Mid(arr(i, 1), 4, 2)
y = Mid(arr(i, 1), 6, 4)
z = Right(arr(i, 1), 3)
s = v & "-" & x & "-" & y & "." & z
arr(i, 2) = s
End If
Next i
Range("B1:B" & Cells(Rows.Count, 2).End(xlUp).Row).Resize(, 2).Value = arr
End Sub