Andrei's comment is a good answer. The one thing I would add is that a 'shift' is usually a fixed block of time that people work, e.g. perhaps a company might have a morning shift from 7-11, an afternoon shift from 11-3, an evening shift from 3-7, and a night shift from 7-11. The 'extra shift' would mean working one of those blocks of time, in addition to the person's normal roster.

Can You Pick Up A Shift Meaning Can You Work On Your Free Time And People Wanting To Pick Up A Shift Is Someone Wanting To Work OverTime

Thanks Andrei

when someone asks if you want to "pick up a shift" it means if you want to work extra hours. So if you were off from work on a saturday and your boss asks you if you can pick up a shift that day, they are asking if you want to work on saturday. when someone tells their boss that they want to pick up a shift, that just means they want to work extra hours on their day off. you usually say pick up a shift when someone is not working. If someone is working and you want them to work longer you just ask if they can stay back or come in early