A stockbroker is a person — or a company — whose job is to buy and sell shares, bonds and other investments for other people. If you want to own a piece of a company but you cannot walk into the stock market yourself, you tell a stockbroker, and they do the buying for you. They charge a fee for this, and that fee is how they earn a living. A broker is a go-between: they are not the owner of the thing being sold and not the buyer either — they stand in the middle and arrange the deal. That is why we also have insurance brokers and property brokers. The 'stock' here means shares in companies. In everyday speech, people often shorten it to 'broker'. The word carries a picture with it: expensive suits, phones, shouting, a lot of money moving quickly. Films use it that way. It is worth knowing that computers have changed this job a great deal — many people now buy shares through an app and never speak to a human being at all — so 'stockbroker' can sound slightly old-world, though the job still very much exists.