This is the 876th most frequent Chinese word.
一边
"Doing two actions simultaneously; on one side."
The word '一边' is used to indicate that two actions are happening simultaneously, in this case eating and reading.
他一边吃饭，一边看书。
He is eating while reading a book.
The term '一边' shows that walking and chatting are done concurrently and in a habitual manner.
他们喜欢一边散步，一边聊天。
They like to walk while chatting.
Here, '一边' is used to describe the multitasking of listening to music and doing homework.