Americans count their lunch breaks as hours worked. The typical "office worker" schedule is 09:00 to 17:00 Monday to Friday with a one hour lunch break from 12:00 to 13:00. This is 8 hours a day or 40 hours a week, but if you are not counting lunch breaks then it is 35 hours a week of actual "work".
Or this comment is made by a European who wants to just diss Americans without realising this situation is largely the same in both places... 😇
Edit: Since there appears to be some confusion here, if a worker had a working schedule of 09:00 to 17:00 Monday to Friday with a one hour lunch break from 12:00 to 13:00, and you asked a European and an American how many hours a week this person works, the American would say 40 but the European would say 35.