score:6
This is explained later in the page:
Der gesamte Saunabadebereich ist Nacktbereich und daher ohne Badebekleidung zu betreten. Die Sauna verfΓΌgt ΓΌber einen Frauen- und MΓ€nnerbereich. Zu bestimmten Zeiten werden diese Bereiche geschlechtergetrennt, gemischt oder als Familiensauna betrieben. Familiensauna bedeutet, dass Familien oder Paaren sowie erwachsenen Einzelpersonen in Begleitung eines Kindes bis zum 15. Lebensjahr der Zutritt gestattet ist.
which in my rough English translation is:
The entire sauna area is a nude area and is therefore to be entered without swimsuits. The sauna has a women's area and a men's area. At specific times these areas are operated with gender separation, mixed, or as a family sauna. Family sauna means that access is allowed for families and couples as well as single adults who are accompanying a child under 15.
So because there are two separate parts, it can operate under two different rules at the same time. On Wednesday, then, one part is women-only and the other part is open to both genders.
If you want to use the sauna together with your girlfriend, go for one of the times marked mixed ("gemischt") or family ("Familien").