I would say there is SOOOO much to do in Yokohama, not only because it's a tourist destination for foreigners, but also because it's a tourist destination for Japanese people. East meets West is a perfect summarization for this area!
Yokohama has a great mix of Japanese food, western food and Chinese food, all in one spot! It also has some of the best coffee spots too, so there are a bunch of hidden gems that you have to explore! Also, since Yokohama is pretty spread out, you'll ...
There are a lot of malls and shops to visit and explore, but make sure to save some room in your bag for the gift shops at the multiple museums you're bound to visit in the area.