Translation:Every day I go to work before they have breakfast.
đều (both) supports mỗi ngày (everyday) to indicate repetition on the action that happens everyday. If "đều" wasn't present here, the sentence would still be understandable but not as commonly used.
So let's say that mỗi ngày - đều sticks together. Example: mỗi ngày tôi đều học trên Duolingo (Everyday I study on Duolingo).
At the beginning, I was like you, wondering why there are some words that appear to be optional, now I understand why they are here, not to make confusion, but it s just more natural to add. Like chinese, some optional words are in the sentences because that's the way the Chinese say ;-)
SLOW DOWN I could barely hear the đ of dều and the đ of đi sounded like vee, but cut off, like v'. And as for ăn sáng, it sounded like ah sai. I could figure out the "every day I work part" , not the go to work, I thought perhaps I am working - as well as the "before they" but I had no idea what they were doing. Can't this guy slow it down? Can't he annunciate better? Yes, I understand real people do not speak all that clearly. But we're supposed to be learning here.