This could mean one of many things, so don't be fooled!
It might mean the product has less energy (kJ) or fat than the original formula. But it could also mean it's light in colour or flavour, as in 'light' olive oil, or light in cut, as in 'lite' potato chips. Read the nutrition panel to see what's really going on.
For more information on health claims made on packaging, read: Reading labels: What the health claims really mean.