With its glossy surface, this postcard does show some surface wear when held at an angle, but looking at it straight on, this real photo that captures the magic of childhood siblings is in overall fine antique condition.
The sepia photo has been colorized by hand: the boy wears dark green shorts and a light green shirt, which matches the green bodice of his sister's dress. The rest of her dress is a pastel peach color. Her diaphanous gown and her curly hair bundled atop her head coupled with the faux forest background gives this scene a pastoral Greek feeling, in my opinion. Very magical all around.
The postal franking is not clear but possibly 1912.
Size: about 5.5 by 3.5 inches. The bottom right corner tip is creased, but as mentioned above, overall, for its age, well preserved. Sorry, I'm not familiar with the printer DLG but from the quality/style, I strongly suspension this is German printed.