What is the meaning of 5-star hotel?

Without you saying the country involved, that is a complex question. Hotels are rated differently in every country. In most of Europe and Britain, a 5 Star rating is "Luxurious" , meaning the hotel provides extra services such as a sauna, a gym etc. In USA ratings are given by AAA and the Mobil travel guide and are different to the European ones. - You would really have name a country to extrapolate this.