A cinematic video is a video that resembles a film. Over the years, the movie industry changed quite a lot in terms of aspect ratio, colour, and lighting styles. When we use the term "cinematic," this means it looks like an actual film we see in theatres.
"Cinematic" is quite liberally used today, and most people relate it to the black bars or wide-screen frame ratios. This term has the same explanation as if you say "this photograph is like a painting."
In the past, “cinematic” was widely used to describe the look of movies shot on film. One could find a “cinematic” film look in photography, advertisements, or design. With the development of digital video and the revolution of run-and-gun videographers, weekend DPs, and YouTube vloggers, the term has become a catch-all for anything that hearkens back to cinema and film — whether that’s colours and aesthetics, or other aspects such as frame rate or shutter speed — or even camera movements, motion, and composition.

Adding a “Cinematic” look to your videos is a fun and exciting activity. But if you really want to get your film noticed, you need to work on your film’s cinematic quality.