Nusa Dua is a resort area with a gated community, with so many five-star resorts, like the Hilton and St. Regis, golf resorts, and fine dining places. It's the most well kept part of Bali and is definitely what we call 'boujee'.
It's is not an island.. which might confuse you if you read the Nusa Islands section above. It's called that because 'dua' means two, refers to the 2 islands attached on the coastline there!
Even if you're not staying at one of the resorts there, you can still visit - Phil hasn't been but Mel went with some friends for a girl's day out at Le Bleu, and said the beaches were beautiful and the park on one of the 2 islands was lovely.