What does fev1 represent? What is considered to be a good fev1 level?

Lung function. The fev1 stands for forced expiratory volume in the 1st second of a lung function test. It gives a picture of how fast the air is able to be expelled from the airways. A "normal" number is really dependent on multiple factors, but generally >80% predicted is acceptable.
1-sec breath out. Fev1, or forced expiratory volume in 1 second, refers to a test that measures how much air a person can blow out in 1 second of a forced exhalation. Normal is >70% of the volume predicted for your height, weight, and age.