Hello,
This makes sense. If this is your first introduction, the diagram shows a lossless transmission line (coaxial cable, two wire line, microstrip, strip line, etc) with source and load. The cable parameters are Z0 and beta (2*pi/lambda).
It is used to explain the concept of interfering travelling waves (that cause change in impedance and standing waves) This concept can be applied to any other medium that supports waves (sound, RF waves, waves in liquid, etc).
In non-guided wave propagation (such as radiowaves), the math is more elaborate as the reflection depends on the angle of incidence. The interference between the reflected waves and incident waves depend on their mutual orientation (complicating the math).