I need macro that would enter date in column L if ANY value is entered in
column B

I think this code of Dave Peterson could be modified to acomplish this task

With Target
If .Cells.Count > 1 Then Exit Sub 'one cell at a time
If Intersect(.Cells, Me.Range("b:b")) Is Nothing Then Exit Sub

On Error GoTo errHandler:

If IsNumeric(.Value) Then
'.Style = "Percent"
If .Value = 1 Then
Application.EnableEvents = False
With .Offset(0, 3)
.Value = Now
.NumberFormat = "mm/dd/yyyy hh:mm:ss"
End With
End If
End If
End With

errHandler:
Application.EnableEvents = True

End Sub