The filename Skyrim - Voices-en0.bsa tells us exactly what is inside if we deconstruct it:
BSA files typically contain:
represents the "vocal soul" of the game’s English version. As a Bethesda Softworks Archive (BSA), it acts as a highly organized digital container that houses thousands of compressed audio files, ensuring the vast world of Skyrim remains immersive and articulate. The Container and the Content Skyrim - Voices-en0.bsa