"Two less hours" or ""two hours less? Neither one is correct. As Stacey said, it should be "two FEWER hours."
Few is used for nouns that you can individually count: hours, dogs, days, cars, etc.
Less is used for nouns that are grammatically singular, and you can't individually count: time, patience, water, etc
Examples:
I worked fewer hours yesterday.
I worked less time yesterday than I did today.
I have fewer water bottles than Mary.
I have less water in my glass than Mary.
I eat fewer candy bars because I am trying to lose weight.
I eat less food because I am trying to lose weight.
In everyday life, people often use "less" incorrectly. For example, in most U.S. supermarkets there is a special line (queue) for people who aren't buying many things. The sign for this line says, "10 Items or Less" or "12 Items or Less," even though the grammatically correct way is "10 Items or Fewer".