Looks like a Light Brahma pullet to me. Brahmas are one of the breeds that don't have the long, sticking-upwards tails like some breeds. She has a little bit of tail in the pictures.
It's a hatchery Light Brahma. Just like you bought.
Roosters are darker and grow their tails slowly. But your bird is pretty old to not have any sickle feathers yet. So gender is not positive. It appears a rooster. But I bet it's a hen.