Inflation

People use money because they assign value to it. This value comes from the fact that they know that other people will accept their money in exchange for stuff that they want. When inflation occurs, the value of money decreases, so people won't want to use it as much. Usually, there is a certain, small amount of inflation at all times, which, because it is constant, does not significantly affect the economy. However, when inflation is unexpected, people's money will suddenly become less valuable, and people will try to get rid of their money as quickly as they can. Because everyone is now trying to get rid of money, the money becomes even less valuable, prolonging the problem. This sudden drop in value makes people trust the money system less, and, if the inflation is large enough, people will start bartering and stop using money all together, like they did in Germany, post World War 2, or, more recently, in New Zealand.

GDP

Real GDP growth means that the economy will be stronger, which means that businesses will grow and be able to produce more stuff. since they are producing more stuff, they will hire more people and pay those people more because more people are buying their products. For average citizens, this means a higher income and a lower price of goods. However, real GDP does not take other factors into account, like the environment. It also doesn't take leisure time into account, only money spent contributes to a countries GDP.