How detailed a response are you looking for? In a nutshell, the Sec proteins are involved in one of the secretory pathway mechanisms that some bacteria use to transport proteins across the inner membrane.
The SecYE complex is a major component of the protein translocation apparatus in the cytoplasmic membrane of bacteria. What is the context? Are you doing research into something?
Actually homologues of at least SecY and SecE have also been identified in eukaryotes. But there is an enormous amount of info out there regarding the sec system. So without specific questions there won't be much feedback, I guess.
