"To come into money" is to suddenly become rich through no action of your own. Usually, it refers to an inheritance (i.e. somebody in your family dies and leaves you a lot of money in their will). However, one could also use the expression with reference to a winning lottery ticket, a lawsuit, etc. Examples: "John just hasn't been the same since he came into money... He all of a sudden thinks he's better than everyone." "The first thing you should do if you come into money is invest half of it." "If I ever come into money, I'm going to buy a house on an island and chill for the rest of my life."