Monopoly is a situation in which one company or person has complete control over a particular market [a particular area where a company sells its goods or where a specific type of goods is sold] or industry [a specific area of economic activity], allowing them to set prices and limit competition.
For example, if one high-tech company has a monopoly on the production of smartphones, they can charge whatever price they want because there are no other competitors.
Very Simple Definition:
Monopoly is when one company or person has all the power in a market [a particular area where a company sells its products or where a specific type of products is sold] and can do whatever they want, like charge really high prices.
For example, if there’s only one place to buy a PlayStation 5 in your town, and they charge a really high price for it, that’s a monopoly.