There are many ways of looking at money, but the best way to look at money and what it means to people is to look at the desires of the people themselves, and how then they use money to achieve them.
But first, The typical economics textbook definition would define money as something which all the people in an economy are willing to trade with, namely rather than bartering in everything, which would incur huge transport costs in the economy, they use a piece of paper with no intrinsic value other than what its demand, and willingness to trade with, amongst the population excites.
Now lets look at why people like to have “things” which could be tangible things like a house, or less tangible, such as an education. The greatest desire amongst mankind, when we really consider it, is social approbation. Its not power, fame, greed or freedom. People evaluate their actions by the very same method money gets its value: the value people hold for a certain action. For example a society may approve of a person to be famous. If this is the case, then becoming famous will become a popular thing to do and money, the thing to trade items with, will be spent in trying to achieve this end.
Its social approbation then, to which we can trace back all the things money gives us, and this would lead us onto the topic of what are human desires? Because this is what social approbation stems from. To use the Socratic definition, there are base desires. These are necessary for life and are insatiable, say the desire for food or sex, thus a life spent trying to saitate them is wasted, we should only indulge them. Then you have long-term spiritual desires such as a relationship, which are ultimately looking to a higher purpose of life or cerebral pleasure, less attached to money, though in obvious ways this too could be for the satiation of base desires.
Finally then what is money? Money is what people make it, and what do they make it? a buying tool for the fulfillment of base human desires.