The official languages of Sri Lanka are Sinhala and Tamil.
English is also widely spoken alongside both of these.
There are variety of religions in Sri Lanka of which the largest is Theravada Buddhism. Other religions practiced here are Hinduism, Islam, and Christianity.
Sri Lanka seems to have more festivals than anywhere else in the world and there are no less than 25 public holidays. As such you will often find yourself in the middle of a colorful celebration without much notice which can be the highlight of a trip here for many travelers.
Many celebrations here follow the cycles of the moon and you will find Muslim, Hindu, and Buddhist inhabitants in Sri Lanka which accounts for the number of public holidays every year.