The word "有所" is formed by the verb "有" (meaning "to have" or "there is") directly preceding the particle "所", which functions to nominalize whatever follows it, often a verb or verb phrase. This combination creates a fixed construction that indicates the possession or existence of something to a certain extent, with "所" effectively representing "that which" is had. For example, in "有所改善", it translates to "to have some improvement", where "所" nominalizes "改善" as the object of "有".