Question

What do mean by anterior and posterior parts of an organ?

Answer 1

anterior means  on the front of(frontal aspect) -also known as ventral
posterior means back of (back aspect)-also known as dorsal

Answer 2

If consider a organ and divides that organ into two parts by a imaginary line. The parts which are above the imaginary line are called Anterior parts. the parts which are below the imaginary line are called posterior parts of that organ.