Dividend yield shows the yearly dividend as a percentage of today's share price. A 3% yield means $1,000 invested pays $30 a year in dividends at the current rate.
The yield is not fixed. It moves for two very different reasons, and telling them apart is the whole skill. It rises when management raises the dividend, which is good news. But it also rises when the share price falls, because the same dividend divided by a lower price gives a bigger percentage. So an unusually high yield can be a generous payout, or it can be the market warning that the business is in trouble and the dividend may soon be cut. This is the classic yield trap, and it is why a fat yield alone should never be the reason to buy. The most trustworthy signal is a long record of steadily paid, growing dividends backed by growing earnings.
For context, compare the yield to what a 10-year government bond pays, the standard alternative income investors weigh it against. Bonds have their own risks: inflation can eat the payments, and governments have restructured debt before. But the comparison still tells you something. If a steady, growing business pays clearly more than the bond, you are being paid to wait while the business compounds.