My interpretation of this would "business casual". In my experience (western culture) this means a mode of dressing a step down from what I'll call business formal (suit and tie for men). A male - which you appear to be from your profile - dressing business casual would wear a collared shirt (golf/polo-style okay usually) and khaki-style pants. A dress shirt and tie would probably be okay, especially for a first meeting. However, a suit would be too dressy and blue jeans and tee shirt would be too "casual". Your shoes should not be athletic shoes, but don't need to be dress shoes either.
That said, it is impossible to be certain without confirming with them. Some places consider "casual" to be anything goes, including blue jeans (or even shorts) and tee shirts, so it would probably be good to clarify.