Welcome to FlyerTalk,
chasni!
With an Economy award ticket (X) on European routes you will get the same baggage allowance as an Economy Classic/Flex ticket, i.e. one checked bag up to 23kg. If you are Star Alliance Gold you can check an additional bag up to 23kg. You can also take a carry-on bag up to 8kg (maximum size 55 x 40 x 23 cm) plus a personal item. More information may be found here.
https://www.austrian.com/Info/Flying..._lang=en&cc=UK
https://www.austrian.com/Info/Flying..._lang=en&cc=UK