Book The Sunlit Man by Brandon Sanderson

Years ago he had comrades in arms and a cause to believe in, but now the man who calls himself Nomad knows only a life on the run. Forced to hop from world to world in the Cosmere whenever the relentless Night Brigade gets too close, Nomad lands on a new planet and is instantly caught up in the struggle between a tyrant and the rebels who want only to escape being turned into mindless slaves-all under the constant threat of a sunrise whose heat will melt the very stones. Unable to understand the language, can he navigate the conflict and gain enough power to leap offworld before his mind or body pay the ultimate price?