If this is from a recipe I don't suppose it means "a lot of". It should mean, "an appropriate amount of" or "some amount of". Sugar can act as a kind of emulsifier of ingredients such as eggs, oil/butter, milk, flour, etc. (Egg yolks are also an emulsifier.)
Thank you so much RedwoodGrove and Barque!
But I still wonder whether we can use "an amount of" in stead of " a lot of" in other case or not? Is it possible or not? Could you please give me an example?