Complex sentence: He asked the garage attendant what he was listening to and was told about a concert, but because he had spent very little time on Earth, he was unaccustomed to how humans speak to each other and sounded very alien-like.
Split into simpler sentences: He asked the garage attendant what he was listening to and was told about a concert. But because he had spent very little time on Earth, he was unaccustomed to how humans speak to each other and sounded very alien-like.