to enjoy the cool; to relax in a cool place (esp. in hot weather)
大树底下好乘凉大樹底下好乘涼 1.lit. under a big tree the shade is plentiful (idiom)2.fig. to benefit by proximity to an influential person
前人栽树，后人乘凉前人栽樹，後人乘涼, to enjoy the benefits of the hard work of one's predecessors. (idiom)