What kind of plant is this?
You are not the only one to inherit one of these from Grandma! This is a Schlumbergera, more commonly known as Christmas Cactus. They are lovely in bloom, which tends to happen around the holidays, hence the name. They are generally an easy-care houseplant, which can be put outside during the summer. They do need some special care to get them to bloom - they need 14 hour nights uninterrupted by lights, which can be accomplished by covering them at night. Illinois Extension has a good article on their care here https://web.extension.illinois.edu/cfiv/homeowners/111122.html