Macro to get/copy data from multiple secondary sheets to main sheet

See if this will work for you

Sub abc()
 Const shBill As String = "BILL"
 Dim ws As Worksheet
 
 For Each ws In Worksheets
    With ws
        If .Name <> shBill Then
            With Worksheets(shBill)
                ws.Range("a2", ws.Cells(Rows.Count, "c").End(xlUp)).Copy .Range(.Cells(Rows.Count, "a").End(xlUp).Offset(1).Address)
            End With
        End If
    End With
 Next
End Sub