EM wave is basically oscillations of electric and magnetic fields
Let’s agree that if one can measure an oscillation, it’s some kind of wave. By measuring the light from a thermic source, be this an electric bulb in a DC circuit or the sun, you are not able to measure periodical changes in the intensity of the light.
Dimming this EM radiation to a very low intensity you observe that light consists of a stream of quanta (so firstly called by Einstein and later named photons).
The fact that this photons have an oscillating electric and magnetic field was established long before
the technology of ultrashort laser pulses was used to measure these fields for single photons. Hertz measured the EM waves from a spark gap transmitter:
Electromagnetic waves are radiated by electric charges when they are accelerated. Radio waves ... can be generated by time-varying electric currents, consisting of electrons flowing through a conductor which suddenly change their velocity, thus accelerating.
From the behavior of the radio wave you may conclude about the behavior of each of the involved photons. With the knowledge about the emission of photons from accelerated electrons we know in our days that radio waves are an oscillating in intensity stream of polarized photons. Polarization means that the electric and magnetic field components are spatial and temporal aligned.
Both electric and magnetic fields get weaker and weaker as you move away from the source... Could you explain how this works, please.
The emitted photons are indivisible units between their emission and absorption. From a star like our sun, but very far away from us, you may get a stream of single arriving photons. The time between the arrival of these photons is random, you get a very week EM radiation from this star. From a very far away pulsar you may get also individual photons, but this time with a swelling number of photons in a time unit. A kind of wave.