Here's how it's often described:
* Two fish tied together by a ribbon: The two "fish" are actually more like V-shapes, with the "ribbon" being a faint line of stars connecting them.
* One fish is more prominent than the other: The Western fish (the one closest to the constellation Andromeda) is slightly brighter and easier to spot.
It's often helpful to use star charts or online resources to get a better idea of its shape. Don't be discouraged if it's hard to see at first - Pisces is a faint constellation!