They're talking about announcing a shift in tactic. Until recently, "broken windows policing" had been very popular: prosecute the small crimes and you will remove the criminals from the system, before they escalate to bigger crimes.

Even before that, there was a tactic of prosecutors competing with each other to be "tough on crime", prosecuting every minor offense so that people would feel safe. It's popular with voters, but it doesn't seem to work. Most notably, people don't feel safe, even as crime falls and prisons fill up.

Baltimore has problems of its own, and it's clear that whatever they've been doing hasn't worked. So they're announcing a change of tactic. We won't know if it works for at least five years.