When you raise the reverse voltage further, there comes a point at which the reverse current increases rapidly. This point is called the breakdown voltage.
For the used 1N4001 rectifier diode, the breakdown voltage is higher than 50 V.
In ordinary rectifier diodes, you want to avoid the breakdown current. However, there exist diodes takes advantage of this property, the so-called Zener diodes.
As a rule, data sheets do not show the breakdown voltage for ordinary rectifier diodes.
On the other hand you find the information "Peak Reverse Voltage". This is the maximum reverse voltage at which the rectifier diode current blocks the current in the reverse direction.
In the next step you take a look at the I-V characteristics of a real diode.