This is the 6942nd most frequent Japanese word.
マイクロ
"Micro" (small-scale or relating to microtechnology).
Here, 'マイクロ' indicates an extremely small or microscopic size, used to describe tiny objects.
この顕微鏡では、マイクロサイズの物体が観察できます。
With this microscope, micro-sized objects can be observed.
In this sentence, 'マイクロ' is part of the proper noun 'Microsoft', which is a company name and does not directly relate to the meaning of 'micro'.
マイクロソフトは有名なテクノロジー会社です。
Microsoft is a famous technology company.
'マイクロ' here is used as a prefix to '経済学', forming 'microeconomics', which denotes the study of economics on a small-scale level, such as individual and business interactions.