Let's use a basic example of how a dividend might work. Company X has a share price of $100, and you own 100 shares. Company X announces they will pay a $1.50 dividend per share on the next payment date (companies announce dividend amounts several weeks before the payment).
On the payment day, you'll receive $150 worth of dividends. After that, however, the stock price will likely drop the same $1.50 as the company is technically worth that much less after paying its shareholders that amount per share.