What happens if i have a high hdl?

It's good: Hdl is the "good" cholesterol and may be more important than ldl. If your HDL is high, you are at lower risk for heart disease.

HDL NOT Cholesterol: Hdl is a complex particle which carries fat molecules, not just cholesterol. Hdl particle concentrations are measured in µmol/l. Large HDL particles are the protective ones & should be ≥10 µmol/l for low risk. Usually hdl-c i.e. Cholesterol associated with apo-a1 protein, the main organizing protein of HDL particles is measured in mg/dl. But this is not the correct or most important & may mislead.

HDL is not HDLc: High HDL probably refers to hdl-c which means HDL cholesterol. While having high HDL c levels is good for groups of patients, we are not sure what it means necessarily for individuals. See my other answers relating to this subject please. Bottom line, however is that having high hdl-c will not necessarily protect you from other risk factors that need to be addressed such as low LDL or apob or ldlp.