"Keuntungan usaha ini sangat besar."

Translation: The profit of this business is very large.

[kuyaC]

What's the difference between "usaha" and "perusahaan"? I'm not sure, that's why I'm asking.

[Ms.Fixer]

TL;DR -- Activity vs. Organization.

"Usaha" is "effort" or "endeavor" (i.e. a sort of activity) and it is used for non-business activities as well, according to KBBI. Meanwhile "perusahaan" (pe-an) is mainly used in business contexts, and it usually means "company" or "corporate enterprise" as an organizational entity.

Sometimes "business" ("usaha") is run jointly by multiple companies (e.g. business alliance, consortium, or outsourcing). And also one company can run more than one business simultaneously (e.g. Amazon runs the e-commerce business as well as AWS; they are totally different business models). Therefore, "The profit of this business" ("usaha") is not always equal to "the profit of this company" ("perusahaan").