Light is simply a name for a range of electromagnetic radiation that can be detected by the human eye. A beam of light is a narrow projection of light energy radiating from a source into a beam. Sunlight, Moon light is a natural example of a light beam.
Objects like the sun that give out or emit light of their own are called luminous objects. Artificially produce a light beam, a lamp and a parabolic reflector is used in many lighting devices such as spotlights, car headlights, PAR Cans and LED housings etc. Light from certain types of laser has the smallest possible beam divergence, thus producing the most parallel light beams possible.
Light is made of tiny particles called photons. We can also say photons as a packet of energy. These photons travel from one place to another in the form of waves. Visible light is the subset of photons that move at a wavelength range that we can see. longest photon wavelength look red to us, and the ones that have the shortest wavelength look blue to us. All different colors come from different wavelengths of light.
Light as a Electromagnetic radiation has a dual nature as both particles and waves. One way to look at it is as changing electric and magnetic fields which propagate through space, forming an electromagnetic wave.