SOC 2 is an audit framework, from the American Institute of CPAs, for how service organisations handle customer data, assessed against trust criteria covering security, availability, processing integrity, confidentiality and privacy. A Type I report checks design at a point in time; Type II verifies the controls operated over months.
It plays the same procurement role as ISO 27001 with a North American accent: many enterprises ask for either or both. For buyers, the Type II report is the one that carries weight.