The phrase indicates those with high control, often beyond direct influence. We can suggest changes, but the powers that be ultimately make the decisions.
Pro Tip 2/3
Abstract Concept
It's used to talk about authority figures collectively, not about any specific person. The powers that be have yet to respond to our complaints.
Pro Tip 3/3
Resigned Attitude
Often shows acceptance or helplessness towards the decisions made by authorities. I'd like more vacation days, but the powers that be won't allow it.