What does this number measure?
A small red dwarf and the Sun's nearest stellar neighbour. Proxima Centauri is much less luminous than the Sun and invisible to the naked eye. The reference compares the star's diameter, not its distance from our system.
Proxima Centauri appears before the Sun when ordered by diameter because it is smaller. That does not mean that it is closer to us.
The Earth–Proxima distance is another measurement. Distance mode shows why stars become symbolic markers at that scale.
Compare the stated dimensions
The comparison uses the number in each fact sheet: altitude, height, diameter, length or distance, depending on the reference. Two values in metres do not necessarily describe the same property.
Source and limitations
Catalogue order of magnitude; a source is provided, but this measurement has not been individually audited.
Proxima Centauri, a red dwarf: interpreted photosphere and activity; approximate diameter.