Means has three main meanings:

1. To mean something is to stand for an idea, or what a word, symbol, or sign points to in your mind. The word “dog” means a kind of animal, and a red octagon means stop even if no one says the word out loud. You'll see this word a lot in this dictionary, because a dictionary's purpose is to explain what a word means.
2. The methods, tools, or resources you use to achieve something. If you want to build a treehouse, you need the means to do it: lumber, nails, tools, and the knowledge of how to use them. When scientists search for a cure, they use every available means, from microscopes to supercomputers. The phrase by any means necessary describes doing whatever it takes to reach a goal, while by no means means “definitely not” (I am by no means finished with my homework).
3. Money or resources that let you afford things. When someone has means, they have enough money to live comfortably. A family of modest means might need to budget carefully, while a family of considerable means can afford luxuries without worry. The phrase beyond my means describes spending more than you can afford, like buying an expensive bike when you've only saved half the money you need.