Despite the fact that a penetration test is something quite technical, there is not only the IT department that is interested in the results. An three-level approach (executive, intelligence, technical) provides all the meaningful information to the various organizational departments in the appropriate language.
An executive summary section is the high-level view of the security risks identified through the engagement and directs mainly the non-technicals.
An intelligence section directs mostly the mid-level positions that may have a small technical knowledge and provides information as seen by an attacker's eye. It provides meaningful insights on the company's exposure to adversaries, before even caryying out any penetration attempt.
A technical section is the core element of a penetration test report, where among other elements which are analyzed below, includes: every vulnerability discovered along with its proper explaination and rating (OWASP, CVSS, CWE), exploitation steps, risk - impact values and mitigation actions.