Imply means to communicate an idea or feeling without saying it directly.
Anita probably said: "I'm hungry, I would like to eat something cold". Or maybe she said: "It's been months since last time I've eaten an ice cream!" In those ways, she suggested eating an ice cream without saying it literally.
According to Adam Smith, the self-interest represents the personal gain of the individual and actions he takes in order accomplish that self interest. He was a staunch believer in the free market and was against government regulations because he thought that the free market would most benefit the individual and therefore the society. The competition is what makes the the manufacturers produce better products and more of them, while this will spur the costumers to buy those products. When many act in their own self interest, the market will give both to the manufacturers and the consumers.
