Sandy sang along with the words as she lay listening to her favorite radio station. (Para. 1)
Meaning: Sandy followed the words of the song although she was still in bed, listening to her favorite radio station.
along with: in company with, together with
I'll go along with you. 我和你一道去。
There was a bill along with the letters. 信里还附着一份账单。
"As" in the sentence here is used as a conjunction, meaning "while".
As she ran to catch the school bus, Sandy thought of her brother. 在赶校车时，桑迪想起了哥哥。