If you have very very light yellow or green discharge with no smell? What do that means

Get it checked out. Discharge from the vagina can mean several different things, including irritation, a reaction to some medications, a sexually-transmitted infection like chlamydia or gonorrhea, or a non-sexually transmitted infection. In order to distinguish between these things (and treat any infection that might be there), it's important to see a healthcare provider.
See a doctor. Yellow or green discharge from anywhere is not normal and should be followed up with a visit to a physician. It depends on where the discharge is coming from (the lungs, reproductive organs, skin, ears etc) as to what may be causing it and how to best treat it. Even with no odor, this is likely from an infection. For this reason it is recommended that you seek the help of a doctor.