This is important. This starts the dismantling of Obamacare. Under Obamacare, any employer who has as many as 50 full-time employees has to pay a penalty or provide his employees with health insurance and full-time was considered 30 hours a week. By raising full-time to 40 hours a week, much less money will be flowing into government coffers to subsidize insurance premiums. If enough parts of Obamacare do not work, the whole thing will collapse. Obamacare may never be repealed in it's entirety but gradually made unrecognizable and replaced piece by piece.
Many employers had cut their workers from full-time to less than 30 hours a week to avoid the penalty. Not only had this hurt those employees who had their hours reduced but employers at the margin of having 50 employees were finding it more profitable to stay below the fifty employee threshold rather than be penalized. This was hampering the economic recovery and job growth.
The bill defining full time as a 40-hour week passed 252 to 172, with 12 Democrats joining House Republican in voting for the measure. Jim Cooper was not one of the twelve. Next the measure goes to the Senate. Read more about this here: House passes 40-hour workweek for Obamacare; Dems buck Obama veto threat.