"Drink the wine bit by bit, and walk step by step" is the principle of being a man and doing things step by step. Don't try to reach the sky step by step.
And "taking too big a step is easy to get hurt" means being too eager for quick success and trying to finish too many things at once, which may lead to some problems. This sentence reminds people to be cautious and steady in doing things in a humorous way, and not to bite off more than one can chew.
In a word, the meaning of this sentence is to remind people not to rush for success when doing things, but to keep a steady mind step by step to avoid problems or unnecessary troubles.