Your micro:bit continuity tester will beep (micro:bit V2 only) and display a checkmark when the continuity probes are electrically connected. You can use this to test the various breadboard rows and columns, and even probe rows/columns that have been connected together with jumper wires.
(View full-size: continuity-tester-concept.mp4 [1])
Links
[1] https://learn.parallax.com/sites/default/files/content/Python/breadboard/mp4/continuity-tester-concept.mp4