2m is enough to come up with a conceptual design that 'works'. They'll use this money to work on technologies that will make such an aircraft feasible. For the actual manufacture, you'd need a budget in excess of 40 million USD.
As for 'silent', it is a relative term, and does in fact mean 'quieter'. This can be done by simply steering the noise into a direction where no one can hear it (up?) and by improving the aerodynamic performance of the aircraft.