Velocity
How much work a team completes per sprint, measured in its own story points. Comparable only to that team's history.
What it tells you about a developer
Treat a resume claim quantified in story points or velocity as local to that team, since the unit does not travel. Verifiable per-individual output lives in commit, pull request, and release history instead.
Velocity is a planning instrument. Knowing a team historically completes about 30 points per sprint makes the next sprint plannable. Because points are team-relative, velocity comparisons across teams or companies carry no meaning. Using velocity to rank individual developers is a known management anti-pattern.