var
  Form1: TForm1;
  Wort: string = 'Hallo, das ist ein Demo-Text';
  Loop: integer;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  Loop := 0;
  Label1.Caption := '';
  Timer1.Interval := 250;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  if Loop = Length(Wort) then
  begin
    Loop := 0;
    Label1.Caption := '';
  end;

  inc(Loop);
  Label1.Caption := Label1.Caption + Wort[Loop];
end;