Well, you should know that the idea of micro and macro has been around long before the League of Legends was a thing. I knew it from StarCraft, the original one, but I’d guess it is even older than that since these concepts are universal to most types of strategy games.
Put simply, micro and macro refer, respectively, to small-scale and large-scale game concepts. For example, your microgame refers to how well you control your champion, how you use its abilities, how well you manage your mana, and how good you are at CSing, trading, kiting, etc. In sum, micro refers to the moment by moment gameplay of what you are doing with your mouse and keyboard, and how effective you are at it.
Meanwhile, macro refers to the large-scale stuff. Mostly things that help your team push and accomplish its objectives and obtain dominance over the game. Meaning things like when to push, when to freeze lanes, when and who you should gank, when to trade lanes, when the jungle should camp on a lane, and even when and where to put wards — all that falls under macro.
Until you master both micro and macro, you’ll have trouble winning consistently in the game. At times like that, you can always buy elo boost services from sites like this one.