Dimensions are primarily about coordinate systems. They are about the question of "Where is something?".

1D and 2D exist and are used all the time. If you are moving your pawn to e3 in chess, you are using a 2D coordinate system.

If you have an accident and you call emegency systems and tell them that you are at highway kilometre 134.5, then you are using a 1D coordinate system.

Higher dimensionality coordinate systems exist too. For example, if you watch a live-rendered 3D animation (laso not something that's pre-rendered into a flat video), then it's a 4D video. Objects in the video have fourdimensional coordinates: a 3D position and a timestamp. In statistics you often have much higher dimensional data as well.

The idea that there would be an n-th dimension as a physical space is nonsense and it's also not what dimensions are about at all. That's what happens if fiction authors hear fancy terms without understanding what they are about.

Edit: in fact, three dimensions are only enough to describe the position of a thing in real life, but things also have rotation. That's another 3 dimensions. And since e.g. humans can rotate a ton of things, each of these things is another dimension for each rotational axis.