What is pretty in Japanese?

Answer 1

"きれいな" is what we use commonly in Japan, but if you want to say more slang, just say, "きれー". This word also mean, "clean, pure" or, "beautiful" so it's a very nice word. If you' looking at something and you want to say it's pretty, you'd say, "これはきれです！" or even simpler, "きれー！"

(きれいな = Kireina)

(きれー = Kire-)

(これはきれです = kore wa kire desu)

Answer 2

You may say 'kirei.'