Question

What is the meaning of "keep a bower quiet for us" in "a thing of beauty"?

Answer 1

Bower(A shelter under shade of trees) provides protection from harsh rays of sun and provides sound sleep, full of sweet dreams, health & peaceful breathing. So it provides us silence. 

Answer 2

In the poem "The Thing of Beauty" by John Keats, the poet mentions that a thing of beauty is an endless joy and never fades away.

"Keep A bower quiet for us" herein the poet refers to that beauty performs like a shade of the tree, soothing and relaxing. Such an act helps the creatures to have good health and sleep peacefully.