「魚」 (sakana) means "fish." It refers to aquatic animals with gills and fins, especially those caught for food. You use 「魚」 when talking about eating seafood or fishing. Japan has many dishes with 魚, such as sushi and sashimi.

水中(すいちゅう)に住(す)む動物(どうぶつ)で、食(た)べることも多(おお)いです。寿司(すし)によく使(つか)われます。