I want to know the meaning of the short form zly.
I have no idea what "zly" means but I do know that if you want to post on this forum, you will have to use English and not text-speak.
I echo what Bhaisahab said. You need to use full words in your posts in future, please.
As far as your question is concerned, the only thing I can think of is that it might be a text-speak abbreviation for "easily" but I've never seen it before.