In physics, the motion of objects depends on the reference frame from which it is observed. The concept of relative motion states that the motion of an object can appear different depending on the observer's perspective.
When we say that a photon is "stationary" from its reference frame, we are referring to the fact that, according to the theory of special relativity, photons always travel at the speed of light (c) in a vacuum in any inertial reference frame. From the photon's own reference frame, it does not experience time or distance, and it perceives itself as being at rest.
However, when we observe the motion of a photon from our reference frame, which is different from that of the photon, we perceive it as moving at the speed of light. This is because of the phenomenon known as time dilation, which is one of the fundamental principles of special relativity. According to time dilation, time appears to slow down for an object that is moving relative to an observer. As the photon moves at the speed of light, time effectively stops for it, and it covers vast distances in no time from our perspective.
In summary, the motion of a photon appears different from different reference frames. From its own reference frame, it is stationary, but from our reference frame, it moves at the speed of light. This is due to the relativistic effects described by the theory of special relativity.