Je ne devais pas être bien réveillé. Il suffit d'ajouter une ligne :
Option Explicit
Sub count()
Dim i As Long, j As Long
Dim nbSheets As Integer
Dim ws1 As Worksheet, ws2 As Worksheet, nbCells As Long
nbSheets = ThisWorkbook.Sheets.count
Set ws1 = Sheets("bilan")
For i = 2 To nbSheets
With ws1
.Cells(i + 5, 1) = Sheets(i).Name
Set ws2 = Sheets(i)
nbCells = ws2.Cells(Rows.count, 1).End(xlUp).Row
.Cells(i + 5, 2) = nbCells - 1
For j = 2 To nbCells
.Cells(i + 5, 3) = .Cells(i + 5, 3) + ws2.Cells(j, 27)
If ws2.Cells(j, 27) = 1 And ws2.Cells(j, 7) = "B" Then .Cells(i + 5, 4) = .Cells(i + 5, 4) + 1
Next j
End With
Next i
End Sub