Click on the "Generate" button to produce a random integer in the closed interval between the specified boundaries. For the random generator to work precisely, these numbers should not have more than, say, 14 digits.
Click on the "Generate" button to produce a random unsigned 64-bit integer in hexadecadic ("hexadecimal" is wrong as it mixes Greek and Latin) notation.
Click on the "Generate" button to produce a most secure password. If the checkbox "Alphanumeric" is checked, then the password consists of random latin letters and digits, otherwise of arbitrary printable and non-whitespace ASCII characters.
The random generator needs a certain "entropy" for producing really unpredictable random numbers. For collecting this entropy it needs some time, which you can shorten by contributing user interface events like cursor movements.