The axon is the part of a neuron that sends the signal to the synapse. Axons are long, thin and tendril-like.
Axons are much like a highly developed dendrite.
The axon carries an electrical signal from the cell body (soma) to the synapse. There the signal passes to other neurons or to muscle fibers. An axon can be over a meter long in humans. Or even longer in longer animals like elephants and whales.