Most ceiling fans have a switch that lets you change the direction of the blades so they rotate clockwise or counter-clockwise (some fan manufacturers label this “forward” and “reverse” respectively)
The reason for two directions: one direction, the blades force air down into the room, creating a cool breeze that blows against your skin and makes you feel cooler and more comfortable when it’s hot outside. Although the fan doesn’t actually cool the room, you can turn your thermostat up a little bit because you’ll feel cooler.
In reverse, the blades create a subtle updraft, which pushes the warm air that naturally rises to the ceiling back down into the room. Again, the fan doesn’t actually warm up the room, but it can make it feel warmer so you’ll be comfortable enough to get by with lower thermostat setting when the weather is chilly.
It used to be that every manufacturer would advise homeowners to set their fan blades to spin counter-clockwise in the summer and clockwise in the winter. That’s often still true, but not for all brands.
The better way to determine which direction to set your fan blades is to turn the fan on and stand under it. If you feel a cool breeze on your skin, you’ve chosen the “summer” setting. If you don’t, reverse the direction of the blades.
When the season changes, flip the switch so the blades spin in the opposite direction.
A caution: Turn the fan off before you flip the forward/reverse switch, which you’ll find right between the blades. And stand on something sturdy to help you reach it.