They told me my dads heart is only working at 30% what do that mean?

Ejection Fraction: This usually refers to the ejection fraction, or the percentage of the ventricle's volume that it pumps out on each beat. It is a measure of how efficiently the heart is pumping. Anything over 50% is considered to be normal. 30% is low, but not dangerously so. I'm sure your father's doctor's provided him with some sort of treatment and follow up plan. It is important that he stick with it.