Body = thickness, aka mouthfeel, aka strength of flavor and texture. (I’m simplifying here.)
Mature = complex. Simple wines that can be opened while young are usually straightforward in the same way that soda is sweet.
We are trying to describe a wine but we don't have words that really fit these particular senses. So we develop a jargon that is at least largely consistent across the ecosystem so when somebody describes a wine as "high minerality" you understand if you've tasted other wines also described this way. The fact that a wine isn't actually "dry" in a literal sense (it is almost entirely water, after all) doesn't matter once you've got a bit of experience matching the jargon to prior experiences.
Next time somebody tells you a wine is "high tannin" or "fruit-forward" or "thin", ask what dimension they are talking about here and try to remember it. Next time somebody says this you'll be able to predict what the wine will be like or you'll know to ask a professional for wines that match the particular things you like.
But there are totally resources. If you want to go in deep, I suggest https://www.thegreatcourses.com/courses/the-everyday-guide-t...
I always thought it was all pretentious claptrap, until a bar owner gave me a glass of 'wine from where I'm from". Wow! My description? "Dry, full-bodied, heavy", then, there where the _several aftertastes is how I'd describe it, and i later bought several bottles. As a dark-beer drinker i was knocked out by this stuff, and did (finally) understand how some descriptions can be applied. I've tried a few different wines in a few different bars since, and the vast majority have been a very easy "light, fruity....and shite".