On the backs, at the tops, this series of five is marked in German and French as "Postcard," just in case there was any doubt. Marked beneath in other languages as well, including Polish.
Measurements are the standard 5 1/2" x 3 3/4", with a story depicted of a young woman and her chaperone sitting on a bench near a river. A fellow in a jaunty cap approaches, greetings are exchanged, the duenna falls asleep, and the young lady puts a finger to her lips as she considers her options. The rest of the story is left to our fertile imaginations.
No writing on the backs, though these cards were obviously ensconced in an album of some sort as there are marks on the backs of three of the set. Additionally, while it's not noticeable from the front, there is some separation of the cards' cardboard material after a century, this being easier to see on the cards' undersides. (Last photo.) Otherwise in excellent condition for keepsakes of this era.