It's peals of laughter - meaning loud or ringing.
It is something that you do when you are happy and you let out giggles, laughs, or possibly a fart or two...
Its not, its been proven that laughing really hard and good at least once a day actually expands your life.
There is no god or goddess of laughter.
Laughter attracts joy, releases negativity, and a lead to amazing cures :)
Funny stuff obviously makes you laugh, nervous situations sometimes make you laugh nervously, or you could force a laugh to pretend you find an unfunny joke funny.