The two major ideas in "The Wealth of Nations" are a free market and an invisible hand.
A free market is an economic system with little to no government interference.
The invisible hand is the idea that people's self-interest helps them make decisions that benefit themselves, and in the long term, society.
The central thesis of Smith's The Wealth of Nations is that our individual need to fulfill self-interest results in societal benefit.
He called the force behind this fulfillment the invisible hand.
Adam Smith tries hard to get his ideas across in a clear way, but the fact remains that this is an economics textbook from 1776.
So, um, it's not the easiest of reads.