When girls have an orgasm, the liquid comes out, what is it called?

Normal discharge. Due to arousal and orgasm, the vagina becomes wet due to fluid expressed through the walls of the canal (transudate). At orgasm, bartholin's glands and skenes glands secrete a white/milky discharge in response to sex. This is normal. Some women "ejaculate". This is the release of urine/secretions through the urethra with orgasm. Some say it's due to gspot activation. This is not fully undertood.
Depends. Mostly that fluid is given nicknames such as "spooge". The liquid comes from glands with in the vagina called skene's glands. The fluid is a combination of mucous and other liquids produced by the vagina.