It is the sign that we see at almost every super-market. Less is supposed to be followed by a uncountable noun. One person had explained to me that five items in the sentence was not the number or countable noun rather it was a quantity, therefore the sentence is correct. He gave me some more examples: My house is less than 3 miles from the school. My car get less than 10 miles per gallon. Could someone explain to me how the number + uncountable noun changes to quantity concept, please.