MATCHING CODE

Hi Pro,

I have this code from this forum.
Now i would like to modify this code as per my current requirement.
Can someone explain to me this code?
Beside delete of column M which will only left the no with "3000". What else they will delete?

Code:

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Sub MATCHING()    Dim a, i As Long, x As Range, dic As Object
    Set dic = CreateObject("Scripting.Dictionary")
    With Sheets("AC")
        .AutoFilterMode = False
        a = .Range("m3", .Range("m" & Rows.Count).End(xlUp)).Value
        For i = 1 To UBound(a, 1)
            If Not dic.exists(a(i, 1)) Then
                dic(a(i, 1)) = Empty
            Else
                If x Is Nothing Then
                    Set x = .Rows(i + 2)
                Else
                    Set x = Union(x, .Rows(i + 2))
                End If
            End If
        Next
        If Not x Is Nothing Then x.EntireRow.Delete
        With .Range("m2", .Range("m" & Rows.Count).End(xlUp))
            .AutoFilter 1, "<>3000*"
            .Offset(1).EntireRow.Delete
            .AutoFilter
        End With
        With .Range("m2", .Range("m" & Rows.Count).End(xlUp))
            If .Rows.Count > 1 Then
                .Offset(1, 2).Resize(.Rows.Count - 1).Formula = _
                "=if(trim(n3)="""",""PX"",if(iserror(match(n3,'TC-CATS'!s:s,0)),""X"",""""))"
            End If
        End With
    End With
    MsgBox "Match Completed! " & vbCrLf & ""
End Sub

---

TIA

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