In Java, variables are used to store data. A variable name is a label that is used to identify and refer to that variable in the program. When you declare a variable, you must give it a name so that it can be referenced later in the program.

Variable names in Java must follow certain rules. They cannot start with a number or contain spaces or special characters. They must begin with a letter or an underscore character. Java is case-sensitive, so uppercase and lowercase letters are distinct. For example, the variables "age" and "Age" are two different variables.

It is important to choose meaningful and descriptive variable names that make the code easier to read and understand. For example, if you are storing the age of a user, you might choose to name the variable "userAge" or "ageOfUser" instead of simply "age".

Good variable names also follow a standard naming convention, such as using camelCase, where the first word is lowercase and subsequent words are capitalized, as in "firstName" or "lastName". This convention helps programmers to easily read and understand the code.

In summary, the variable name is a label that represents the variable's value and should be chosen carefully with good naming conventions in mind to create clear and understandable code.