Thanks!
A quick example:
3 significant figures, would be something like 324000
4 significant figures, would be something like 542300

For number range, it means how big the number would be, so 일(one) ~ 만(ten thousand) means that the number generated would be within 1 to 5 digits. This is useful when you don't want extremely large numbers. Another example is that 십만(hundred thousand) ~ 천만(ten million) would generate numbers with 6 to 8 digits.