Ruta 6 is a homoeopathic product prepared from the common rue. The 6 stands for the sixth potency, in more human terms the sixth dilution.

A so-called mother tincture (Ruta Q, the Q stands for ‘mother tincture’) is prepared by macerating the plant in alcohol of varying strength for varying lengths of time. This mother tincture is then diluted by mixing 1 part with 99 parts alcohol or water, 6 times in a row, resulting in a 10¹² dilution.

Dutch: Wijnruit
English: Rue, Common Rue, Garden Rue, Herb-of-Grace, Bitterwort
French: Rue odorante, Rue des jardins, Herbe de grâce, Péganium
German: Raute, Weinraute, Gartenraute, Weinkraut
Scientific name: Ruta graveolens

References:
[1] Koninklijk besluit betreffende de fabricage van en de handel in voedingsmiddelen die uit planten of uit plantenbereidingen samengesteld zijn of deze bevatten, 29 August 1997
[2] Rue (Rita graveolens L.), Gernot Katzer’s Spice Pages, Retrieved 21 January 2011
[3] Ruta graveolens, Floridata, Retrieved 21 january 2011
[4] Ruta Graveolens (Rue-bitterwort), William Boericke, Homoeopathic materia medica, Retrieved 21 January 2011
[5] Common Rue, Wikipedia, Retrieved 21 January 2011