The following code was provided as a solution to this issue.
Ideally what I would like is to look at column D and if it is not blank "" then look at column J and take the first 5 digits and put them into column O
 
Sub Test()
Dim c As Range
With Sheets("Sheet1")   'amend as appropriate
    For Each c In .Range("D2:D" & .Cells(Rows.Count, "D").End(xlUp).Row) 'assumed header in row 1
        If Not IsEmpty(c.Value) Then
            c.Offset(, 11).Value = Left$(c.Offset(, 6).Text, 5)
        End If
    Next c
End With
End Sub
What does the use of the .Text in line 6 provide, given that all we are seeking is the first 5 characters of the cell value?