Koi are a kind of ornamental carp. They are kept for their pretty colors. Koi get quite large when they grow older, especially if they are kept in a large enough pond.
Samoyeds are large, long-haired white dogs from Siberia. They were bred to herd reindeer, to pull sleds and to keep their owners warm at night. They are a very energetic breed and need lots of space and regular exercise or they will get bored and destructive. They are friendly dogs and don't make very good guard dogs. One of their interesting features is they don't have a 'doggy' smell and they don't shed much, so are classed as 'hypoallergenic'.
Soy is a common name for the soybean plant, and many things that are made from it.
A toy is something that is designed for a child to play with. Most toys are just smaller versions of real things, like toy trains and cars, stuffed animals, dolls and teddy bears.