とりあえず、コードを1行ずつ説明します。
A列のセルの中身を左から9個だけ取り出す
ws.Cells(i, 2) = Left(ws.Cells(i, 1), 9)
取り出した9個の中から〒マークを消す
ws.Cells(i, 2) = Replace(ws.Cells(i, 2), "〒", "")
最後に - を消す
ws.Cells(i, 2) = Replace(ws.Cells(i, 2), "-", "")
全貌
Sub ExtractZipCode()
Dim i As Long, LastRow As Long
Dim ws As Worksheet
Set ws = Sheets("Sheet5")
LastRow = ws.Cells(Rows.Count, 1).End(xlUp).Row
For i = 2 To LastRow
ws.Cells(i, 2) = Left(ws.Cells(i, 1), 9)
ws.Cells(i, 2) = Replace(ws.Cells(i, 2), "〒", "")
ws.Cells(i, 2) = Replace(ws.Cells(i, 2), "-", "")
Next i
End Sub