Please explain me this term from heart echo report: only minimal, not fully anechoic separation behind the rear wall of the left ventricle. is it ok?

Fluid in heart sac: The heart has a thin lining called pericardial sac. U'r finding usually indicates there is fluid between the space of the heart muscle and the sack called a pericardial effusion. It can cause chest discomfort or pain. Usually is followed closely by the heart doctor. Rarely needs to be drained-in emergency cases or other very special circumstances.