A breadboard originally was a flat wooden cutting board used to support a loaf of bread (or other foods) while it was being sliced; this original meaning is still in use, but has a new additional meaning as “a base for prototyping”. from wikipedia

Internally, breadboard is electrically connected in this way (pink line)

Here is the correct connection example

The electricity will flow this way (pink line), thus the LED will shine.

and here is the wrong connection

The electricity will flow this way (pink line), making blue and red wire (+ and -) shortcut!