Student workers are enrolled university students taking on paid positions at their campus. They perform simple tasks to assist the campus staff in all kinds of different jobs that are necessary for running the campus.
There are various roles they can fill as student workers, from office assistant to a helpdesk support agent, facilities department escort, or campus events staff, and more. These positions are created by the universities to financially aid students while providing them with opportunities to learn practical work skills.
The tasks vary with the roles: student workers do administrative work filing and typing documents, they carry out deliveries, answer the phone, make photocopies, or assist in academic research and lecture preparations. They help to maintain the IT facilities of the campus, help to resolve students' issues, carry out community service, work on organizing events at the campus, or help with the maintenance of campus buildings.
The jobs are, of course, part-time positions so you can easily work around your academic duties.