What does it mean if my triglyceride level is low?

Not abnormal. No adverse implications unless a marker for extreme weight loss by diet or illness. Check with your doctor, but congratulations!
In General OK. Low triglycerides in general probably mean a good diet, or lifestyle, but can be a sign of malabsorption, or gastrointestinal illness. Assuming one is healthy, then low tg's are a good thing. Some patients have an inherited condition that does not allow them to absorb/transport fat and cholesterol, leading to very low cholesterol and tg levels and fat soluble vitamin deficiencies. See your doctor.