From the name of this shop you can probably guess they sell lots of candy and cookies. The shop is attached to Emporio, and they're so well integrated it's hard to tell you're moving between one and the other.
The Japanese are by and large perennial gift givers. It is customary in Japan that when going on a trip you bring home some small presents to give to family and friends. Because of this, many of the items you'll find in Valentina's Sweets are packaged just for gift giving. This is a good thing, even if you're not going to give the items away as gifts, as many of the packages are high-quality metal boxes that make great souvenirs, even after you've eaten the sugary contents.