Reporting on social media is an important factor in making future decisions on developing your social media and knowing more about your clients needs and interests, exactly like using analytics to understand your users' behavoir on your website & mobile app.
The purpose behind social media reports can be diverse as it is a way to answer questions about the visibility of your brand, sentiment of conversations, which social platforms are your fans engaging most on and who are the major influencers. Other statistics provided would cover gender, age, geographic location and many more.