As mentioned above, FL370 means Flight Level 370 and 37000 feet.
There are altitudes and Flight Levels. Then what makes them different? Well, altitude is below and FL is above, but how to know when it changes? Easy: when you go up, altitude changes to Flight Level at Transition Altitude (TA) and when going down, FL changes to altitude at Transition Level (TL). In Finland TA is always 5000ft and TL is FL45-FL65 depending on the QNH. The "standard" TL in Finland is FL55. In the US, TA is always 18000ft.
Just to let you understand this:
1) You are told to climb FL70, TA is 8000ft. Is this possible?
2) You are told to descend to FL55 with TL being 50, possible?
3) Climb 7000ft with TA at 18000ft. Possible?
4) Descend 4000ft, TL 35, possible?
5) Descend FL60, TL 55, possible?
Now think of these questions and see if you can answer them. I have told you everything you need to know.
1740 days idle. Beat that.