Modification "option explicit"

Option Explicit

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    Dim c As Range
    If Target.Address = "$AD$1" Then
        Range("Y2:AC100").Value = ""
        ActiveWorkbook.Names("NbClick").RefersTo = "=0"
        Exit Sub
    End If
    If Intersect(ActiveCell, Range("S2:S100")) Is Nothing Then Exit Sub
    ActiveWorkbook.Names("NbClick").RefersTo = [NbClick] + 1
    If [NbClick] = 1 Then
        ActiveWorkbook.Names("Lig1").RefersTo = Target.Row
    ElseIf [NbClick] = 2 Then
        For Each c In Range(Cells(Target.Row, 20), Cells(Target.Row, 24))
            Cells([Lig1], c.Column + 5) = Cells(Target.Row, c.Column)
        Next
    End If
End Sub

Option Explicit
Public NbrClics As Integer
Public L As Long
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Target.Address = "$AD$1" Then
    Range("Y2:AC100").Value = ""
    NbrClics = 0
    Exit Sub
End If
If Not Intersect(Target, Range("S2:S100")) Is Nothing Then
    NbrClics = NbrClics + 1
    If NbrClics = 1 Then L = Target.Row
    If NbrClics = 2 Then
        Range(Target(1, 2), Target(1, 6)).Copy Cells(L, 25)
        NbrClics = 0
    End If
Else
    NbrClics = 0
End If
End Sub

Dim r As Range

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Not Intersect(ActiveCell, [S:S]) Is Nothing Then
  If r Is Nothing Then
    Set r = ActiveCell
  Else
    ActiveCell(1, 2).Resize(, 5).Copy r(1, 7)
    Set r = Nothing
  End If
ElseIf ActiveCell.Address = "$AD$1" Then
  [Y:AC].Clear
End If
End Sub