StinGrid - Inhalt nach Excel exportieren

[Oz der 1.]

Hallo zusammen,
ich bin, was programmieren angeht, noch Anfänger.
Momentan bin ich dabei den Inhalt eines StinGrid's, im Rahmen eines kleines Projektes, nach Excel zu exportieren.
Nach erfolglosen Versuchen habe ich im Internet folgenden
Code gefunden und einfach mal in mein Projekt eingebunden.
Alles funktioniert wunderbar, ohne Fehler.

Das Problem ist,
[b]ich verstehe diese Zeilen nicht!
Und es bringt mir recht wenig, wenn ich net weiß was da im einzelnen abgeht!
Kann mir bitte jemand helfen diese Zeilen zu verstehen

Delphi-Quellcode:

function RefToCell(RowID, ColID: Integer): string;
var
  ACount, APos: Integer;
begin
  ACount := ColID div 26;
  APos   := ColID mod 26;
  if APos = 0 then
  begin
    ACount := ACount - 1;
    APos   := 26;
  end;

  if ACount = 0 then
     Result := Chr(Ord('A') + ColID - 1) + IntToStr(RowID);

  if ACount = 1 then
     Result := 'A' + Chr(Ord('A') + APos - 1) + IntToStr(RowID);

  if ACount > 1 then
     Result := Chr(Ord('A') + ACount - 1) + Chr(Ord('A') + APos - 1) +
     IntToStr(RowID);
end;

function StringGridToExcelSheet(Grid: TStringGrid; SheetName, FileName: string;
  ShowExcel: Boolean): Boolean;
const
  xlWBATWorksheet = -4167;
var
  SheetCount, SheetColCount, SheetRowCount, BookCount: Integer;
  XLApp, Sheet, Data: OLEVariant;
  I, J, N, M: Integer;
  SaveFileName : String;
begin
  SheetCount := (Grid.ColCount div 256) + 1;
  if Grid.ColCount mod 256 = 0 then
     SheetCount := SheetCount - 1;

  BookCount := (Grid.RowCount div 65536) + 1;
  if Grid.RowCount mod 65536 = 0 then
     BookCount := BookCount - 1;

  Result := False;
  XLApp := CreateOleObject('Excel.Application');
  try
    if ShowExcel = false then
       XLApp.Visible := False
    else
       XLApp.Visible := True;
    for M := 1 to BookCount do
    begin
        XLApp.Workbooks.Add(xlWBATWorksheet);
        for N := 1 to SheetCount - 1 do
        begin
          XLApp.Worksheets.Add;
        end;
    end;
    if Grid.ColCount <= 256 then
       SheetColCount := Grid.ColCount
    else
       SheetColCount := 256;
    if Grid.RowCount <= 65536 then
       SheetRowCount := Grid.RowCount
    else
       SheetRowCount := 65536;

    for M := 1 to BookCount do
    begin
        for N := 1 to SheetCount do
        begin
          Data := VarArrayCreate([1, Grid.RowCount, 1, SheetColCount], varVariant);
          for I := 0 to SheetColCount - 1 do
            for J := 0 to SheetRowCount - 1 do
              if ((I+256*(N-1)) <= Grid.ColCount) and ((J+65536*(M-1)) <= Grid.RowCount) then
                Data[J + 1, I + 1] := Grid.Cells[I+256*(N-1), J+65536*(M-1)];

          XLApp.Worksheets[N].Select;
          XLApp.Workbooks[M].Worksheets[N].Name := SheetName + IntToStr(N);
          XLApp.Workbooks[M].Worksheets[N].Range[RefToCell(1, 1), RefToCell(SheetRowCount,
            SheetColCount)].Select;
          XLApp.Selection.NumberFormat := '@';
          XLApp.Workbooks[M].Worksheets[N].Range['A1'].Select;
          Sheet := XLApp.Workbooks[M].WorkSheets[N];
          Sheet.Range[RefToCell(1, 1), RefToCell(SheetRowCount,SheetColCount)].Value := Data;
        end;
    end; 
    try
      for M := 1 to BookCount do
      begin
          SaveFileName := Copy(FileName,1,Pos('.',FileName)-1) + IntToStr(M) +
          Copy(FileName,Pos('.',FileName),
          Length(FileName)-Pos('.',FileName)+1);
          XLApp.Workbooks[M].SaveAs(SaveFileName);
      end;
      Result := True;
    except
    end;
  finally
    if (not VarIsEmpty(XLApp)) and (ShowExcel = false) then
    begin
      XLApp.DisplayAlerts := False;
      XLApp.Quit;
      XLAPP := Unassigned;
      Sheet := Unassigned;
    end;
  end;
end;