The phrase "to block the sun" means preventing sunlight from reaching a certain area by placing something in its path, like an object or a structure. It can provide shade or reduce the amount of sunlight that enters a space.
Sentences with «to block the sun»
The canopy blocks the sun from reaching your infant's face. (newmommysplace.com)
He might have known that the moon blocks the sun in an eclipse. (sciencenews.org)
Heat rejection helps you stay cool during the summer by blocking the sun. (geekwrapped.com)