In a multicultural society, there is not an official (decided by the people in charge) culture that every person must be a part of. Instead, all cultures are respected as much as each other.
A multicultural society can result when people from many different countries migrate to one place, or an empire conquers many countries. Tolerance is a big help for multiculturalism. Xenophobia makes it difficult.
A multicultural society would be composed of people from different ethnic backgrounds and cultures living and working together. In society when people from different backgrounds link with each other's culture shows the acceptance of each other's culture and background.