Answer:
Macroeconomics is a very relevant subfield of economics because it studies economic matters at the aggregate level, that means things such as inflation, unemployment, economic growth, investment, saving, and many other economic phenomena that are very relevant for all countries, all governments, and essentially everybody around the world.
Macroeconomics is a contested field, with some points in agreement, but many others in dispute among economists. For this reason, the policy recommendations that are based on macroeconomic criteria are often very different, and frequently clash into political conflict.
Economic policy decisions never produce exactly the expected result, but they often give a satisfactory result (not always). For example, the monetary policy based on the principles of monetarism did manage to bring down inflation substantially ever since it began to be applied in the late 1970s.