I know your inclination is "aw shit that is some leftist propaganda" but it is pretty much just some statistics and infographics gathered by the Washington Post and Bowling State Green University.
It directly states: The 54 criminal prosecutions were identified by Bowling Green State University criminologist Philip M. Stinson and The Washington Post. Cases were culled from news reports, grand jury announcements and news releases from prosecutors. For individual cases, reporters obtained and reviewed thousands of pages of court records, police reports, grand jury indictments, witness testimony and video recordings. Dozens of prosecutors and defense attorneys in the cases were interviewed, along with legal experts, officers who were prosecuted and surviving relatives of the shooting victims.
Since the statistics were gathered by a University I feel like the legitimacy of those statistics are more or less as close to the truth as we can get. And since the article and statistics contained in that report are separate, you don't have to read a Communist Manifesto of how "capitalism is the cause of all suffering" or something like that