What is the check engine light on a 2007 Toyota solara mean?

Check your owners manual for a more complete description.

The light may be advising you of an engine sensor failure. It may also simply be telling you the gas cap wasn't tightened the last time the tank was filled. Check that first. If the cap was left loose it may take a couple of engine starts before the system resets the light. If the cap is tight, drive to an auto supply store that will loan you a code reader. Plug the reader into the port under the dash (to the right of the steering wheel) to find out what the car's computer thinks is wrong.

By the way, don't confuse the Check Engine light with the Maint light. The latter is simply a reminder that the vehicle is due for an oil change. It will blink at engine start 4500 miles after being reset then will stay on solid at 5000 miles. Change the oil, reset the light.

Cheers