1. To be visually appealing or attractive. The new paint looks good. Nice job! You look good today. Is that a new haircut?
2. To indicate a likelihood of something desirable, successful, or impressive; to bode well for the future. Things are looking good for the company after they revealed their financial results for the quarter. We won't know if the surgery was successful until later, but everything looks good so far.
3. To give the appearance of something that is desirable or proper. It will look good on your application if you've done some volunteer work. She'll look good before the panel if she remembers to address each member by name.