The word "about" is a preposition that indicates a topic or subject. It can also refer to the approximate location, quantity, or time of something. Essentially, when you use "about," you're discussing what something is related to or the context in which something occurs.
The word "about" originates from the Old English "abūtan," which means "on the outside of" or "around." Over time, it evolved to encompass the meanings associated with topics and approximate contexts.