"남자는 신고를 당했습니다."
Translation:The man was reported.
당하다 means something happened to someone. It is used in negative circumstances (robbed, in an accident, attacked) usually with the noun, i.e., here it is report (as in police report most likely, noun), followed by the object particle 를, and more often than not past tense 당했어요 (or whatever formality).
도난을 당했어 - I was robbed, 공격을 당했어 - I was attacked, 사고를 당했어 - I was in an accident
wintertriangles, your tips and help in Korean have been very helpful to me throughout the tree, and I thank you for your time in helping learners with the more difficult grammar questions.