Hourglass is primarily designed to help people, who get paid on a hourly base, to calculate their wage.
Especially when not working full hours it can be very frustrating to write down you working times manually.
The Light-Version of Hourglass calculates times between a starting- and endpoint for you, so you have an easier time calculating your payment.
With the Pro-Version you can put in you hourly wage and Hourglass does the rest for you.
In any way a helping hand!