What are the three main parts into which a neuron can be divided? What are their respective functions?

The three mains parts into which a neuron can be didactically separated are: dendrites, cell body and axon.

Dendrites are projections of the plasma membrane that receive the neural impulse from other neurons. The cell body is where the nucleus and the major cellular organelles are located. Axon is the long membrane projection that transfers the neural impulse at distance to other neurons, to muscle cells and to other effector cells.

Image Diversity: neuron structure