Code not working

I did not write this code.  Can someone tell me please what it is doing.  Is it looking for duplicates???

Sub AdRec
Dim r As Range, rw As Long
 
Set r = Sheet19.Range("A1")

If r(3, 1) <> "" Then
rw = FindRec("Cusip_tmp", 1, cusip)
r.Offset(rw, col) = r.Offset(rw, col) + 1

End Sub
__________________________________________
Function FindRec(w As String, numcol As Integer, lookval As String) As Long
Dim r As Range, numrows As Long
Dim I As Long

numrows = Worksheets(w).UsedRange.Rows.Count
Set r = Worksheets(w).Range("A1").Offset(0, numcol - 1).Resize(numrows, 1)
 On Error Resume Next
 I = -999
 I = WorksheetFunction.Match(lookval, r, 0)
 On Error GoTo 0
 
FindRec = I - 1