The yield is the prize you get for investing in something! Sometimes the prize is zero, suggesting the investment made no money but it can also be a high, positive number suggesting huge returns in the form of interest or dividends.
For example…
Nina has a hundred shares in a big pharmaceutical company. If the dividend-price for each share is one dollar per share and the current share price is ten dollars per share, then the dividend’s yield is one divided by ten times a hundred, which comes out as ten percent. That’s a great yield!