A childhood belief about speaking

I used to think that every word meant something; I once asked my sister what “purple” meant, and she just said, “It doesn’t mean anything; it’s just the name of a colour.” On a similar note, I also thought that a word was a short form of saying whatever the definition was. Almost like the definition was the word in another language. Like, I thought that a single word could take the place of a small phrase. A random example would be this: saying “pop” was actually like saying the much longer phrase, “a fizzy, carbonated drink that comes in a variety of flavours.” I would be like, “wow, ‘pop’ means ALL that?” I hope this makes sense. I tried describing my thoughts as best I could.