What does expiratory volume mean? Is it good to have high volume or low?

FEV1. An expiratory volume is usually how much air your expell from your lungs in a unit of time (fev1 = expiratory volume in 1 second). There are predicted normals (based on sex, height, weight and race). A normal number or a number greater than 70 perent of your predicted normal is ideal.
High. Forced expiratory volume in one second. (fev1). Normals values are adjusted to age and body weight. Higher number better.