The work you already did, described as what you produced.
A student applying for internships asked a public forum whether to list classes or skills, and named calculus, physics, chemistry, Microsoft Office, and coding. The thread. The useful replies said: relevant coursework, a project, a campus role, and a skill only if this job uses it. They also said an odd job still counts when you speak to what you accomplished in it.
A course list is not yet that. "Completed calculus" says you were assigned calculus. It does not say what you produced.