Wattage tells you how much power a bulb draws. Lumens tell you how much light you actually get — and that is the number worth shopping on.
As a rough guide: a bedroom is comfortable around 300–400 lumens, a kitchen wants 700–900, and a bathroom sits in between. A 9W LED puts out roughly 900 lumens, which is why it replaces a 60W incandescent bulb while using a fraction of the power.
Colour temperature matters too. 2700K feels warm and restful for bedrooms; 6500K is crisp daylight, better for kitchens and workspaces.