An arrow is a projectile that is shot with a bow. It predates history and is common to most cultures.
An arrow is a long and thin formerly of wood now, aluminum or carbon fiber matrix are common materials, pointed (or armed with an arrowhead if the purpose is hunting rather than target-shooting) at one end and with a notch in the other. Near the notch end are vanes (often three but amany fletchings have four or even more), originally made from feathers but now often made of plastic, which keep the arrow pointed in the direction of travel.
To shoot an arrow with a conventional (long) bow, place the string of the bow in the notch of the arrow, rest the shaft of the arrow against the body of the bow (on its right side if you are right-handed), if there are an odd number of vanes be sure that the arrow is oriented so that one vane is directly opposite the body of the bow, pull back on the string, and let go. Right-handed people hold the bow with their left hand, have their left side facing the target, sight along the arrow (towards the target) with their left eye, and handle the arrow and string with their right hand. The left wrist should be bent outward so that the returning string doesn't scrape the inside of the wrist or catch on a wrist-guard.
Somebody else supply how-to for using a crossbow and maybe something on how arrows differ from darts.
An arrow is a universally recognized symbol for directional movement.