Macau is a former Portuguese colony and is a Special Administrative Region of China, and thus the official languages are Cantonese and Portuguese.
Cantonese, a dialect of Chinese, is the most widely spoken language in Macau. It is the language of everyday life and business for the majority of the population.
Portuguese, despite being an official language, is less commonly spoken among the general population. However, it is still used in some administrative and legal capacities, and you will find many street signs, public transportation information, and government notices in both Cantonese and Portuguese.
English is also fairly common, particularly in areas frequented by tourists such as hotels, major restaurants, and casinos. Other languages you might hear in Macau include Mandarin (due to the influx of tourists from mainland China) and various languages spoken by expatriate workers from places like the Philippines and Indonesia.
Remember, even though English is spoken in tourist areas, it's always appreciated when visitors learn a few phrases in the local language. A simple "thank you" (in Cantonese, it's "M̀h'gōi" when receiving a service or "Dòjeh" when receiving a gift) can go a long way.