Today were going to examine the difference between words that indicate number and those that indicate quantity or amount. Words indicating amount are words like less, little and much. Words used when referring to number are words like few, fewer and many. Basically amount words refer to things that are measured in bulk or volume, while number words refer to things that can be counted.
You'll drink less lemonade if you drink fewer glasses.
The amount of lemonade in a container (even if that container is a person) is measured in volume, so we use less, but the number of glasses can be counted, so for that we use fewer. The word more can be used for either one.
A common mistake is to use an 'amount' word (e.g. less) when referring to people. People can be counted, so use few, fewer or many. On the other hand, 'amount' words are correct when referring to units of time or money, unless you are speaking of specific coins or bills (e.g. fewer pennies).
I hope you found this helpful. Thanks for visiting. :)