The notion of dimensions and dimensionality stems from mathematics, but is also a core idea in physics. The mathematical definition of dimensionality is that the dimension of an object is defined by the minimum number of coordinates needed to specify each point within it. A point is a 0-dimensional object, a line is 1-dimensional, a plane is 2-dimensional, and 3-dimensional objects are the ones we all know and love, consisting of 3 dimensions of length, width, and height. These are traditionally known as dimensions of space. There are other interchangeable ideas within this concept artistically, such as a line is a series of infinite points, a plane is a series of infinite lines, etc. With the exception of shadows on a surface, these concepts are real, but not physically real; they are imaginary.
If you draw a line, although it's negligible, the line still has width and length like a plane. The fact that the line exists in a material form means it exhibits 3 dimensions of space, and is not physically a 1 or 2 spatial-dimensional object. You could then go and find an "edge," and say it forms a straight line, but it's still an attribute of something—it's not empirically "a line." Even then, you could magnify the edge, and see that "the edge" has multiple edges.
The idea of "dimensions," in the context of consciousness experiencing reality, has been thought to mean many different things. Time itself is considered a dimension. Simply put, for the sake of this model: Dimensions of consciousness are foundational experiences within reality.
Time + Space + Force = 3D Consciousness Experience
Time = The Experience of a Relative Measurement of the Rate of Change
Space = The Experience of Size and an Illusion of Separation between Physical Phenomena
Force = The Experience of Different Expressions of Attraction and Repulsion
This dimensional trichotomy allows for the human experience of a physical universe. From this perspective, "dimensions" could be more accurately termed "dimensional experiences." Dimensions aren't places; they are special effects that generate the perception of reality.
Space is the experience of size, distance, and volume, relative to the observer's perspective. The term "distance" is the measurement of that which is defined as separate from something else, and the experience of how far apart objects are. The overall experience is comparable to a virtual reality simulator. The space being experienced doesn't actually exist—it's an illusion—yet the experience of that dimensional illusion is real. As an oversimplified comparison, your experience of 3D reality is somewhat similar. Fewer limits, different projections of light, and sometimes you might encounter a boss or two. Obviously real life is a "bit" more complicated. :)
Force is what accounts for all physical experiences of attraction and repulsion. Attraction and repulsion are responsible for just about everything—it is the orchestrator of the physical universe. The term "attraction and repulsion" is a simplification of a concept known as "non-contact force"; i.e., the four known fundamental interactions. Electromagnetic and gravitational interactions dominate the commonly identified events in day-to-day life; however, in layman's terms, the term "attraction and repulsion" is being used to denote the organizing principle of space and time. This dimensional effect holds everything together, and the stronger the attraction, the more two seemingly separate things appear as one. This happens on a micro level, wherein atoms attract and repulse, making things like a rock and even your own body seem solid. On the macro level, gravity holds you down to Earth, holds Earth in orbit with the Sun, and the Sun in orbit with the Milky Way, et cetera. Magnetism, gravity, and principles of attraction and repulsion are what organize your perception of the physical universe.
Time is the experience of change with continuity, and is the conduit of all experience. The experience of space and gravity, in and of themselves, are created within time. The perception of "things happening" is the perception of things changing, and the only way to comprehend that experience of change is to create the notion of "before, present, and after," which is also what time is. It is the measurement and recognition of change in your reality, and is a type of dimensional path you are constantly going down to experience your existence.