Someone who’s nouveau-riche has recently become wealthy and enjoys spending money. Your nouveau-riche neighbor might buy six expensive cars and put lion sculptures in his front yard.
The term nouveau-riche is a derogatory term meant to mock people who have a lot of money but don’t have the good taste to spend it in a “classy” way. The implication is that it’s more socially acceptable to inherit money and the long traditions that go with it than to suddenly become wealthy. Nouveau-riche, “new rich” in French, dates from 1813, but the idea goes back to the ancient Greek concept of neo-ploutos.