Confusing Part

[rohit817]

https://github.com/SasirekhaPV/Wipro-Training-Module2---A-Video-Rental-Inventory-System/blob/b710930ca927539ecea09ddaf6fc7993d63e4fb6/src/com/w3epic/wiprotraining/bean/VideoStore.java#L4

Respected Sir,
In this line ,I am not getting what it is,how it is working and what was the reason to create it? Can you make me understand.I am new to learn in java.Please help me sir and provide me a knowledge of this with simple example.