The Breadboard is a platform for prototyping or circuit assembly platform which helps ease out the connecting of different electronics component. It has holes, letter, numbers and connection lines designed to easily spot a point in your circuit.
The first picture below shows an example of a circuit connection assembly, the second picture on the right shows the bottom of the breadboard which the sticker is peeled to show how the metal holes are connected to each other.
As shown below, the way the points are connected together is shown in yellow colored segment. Point 1A to 1E is connected to each other, point 2A to 2E is also connected to each other BUT line 1 and line 2 are not connected to each other, and so on. On both sides we have blue (-) and red (+) lines where the 2 lines are not connected to each other but each of them have 1 row of 25 points/holes available.