Você está procurando o Worksheet_change
evento
Occurs when cells on the worksheet are changed by the user or by an external link.
Exemplo
Sub Worksheet_Change(ByVal Target As Range)
If Range("B7").Value = "Hide" Then
Rows("7:7").EntireRow.Hidden = True
ElseIf Range("B7").Value = "Show" Then
Rows("7:7").EntireRow.Hidden = False
End If
End Sub