In practice most of the common explanations I've seen mean "take a lot of the money from the police and give it to people more qualified to do things that police are filling in for" — so things like social work, for example.
This would also benefit the police, because they could focus on stopping and investigating actual crime.
A common example... if there's a homeless, mentally ill, or otherwise distressed person rambling on the sidewalk in front of your house for an hour... in the US many people would call the police. This is a terrible application of force and innocent people have been shot this way.
With properly staffed and funded social workers, someone could theoretically call them first, and then that person if needed could decide to escalate.
So really "defund the police" in a pithy slogan — "reduce funding to the police so it can be directed to more purpose-fit response teams" doesn't quite roll off the tongue the same way.
This same criticism is levied towards "black lives matter" — some take it as "only black lives matter" (often intentionally despite having it explained to them). So the response is "all lives matter" but the general intent is actually "black lives matter as well." Earlier "vote or die" was sometimes criticized in a warped way of "vote or we'll kill you"
There's this strange insistence that political slogans be perfect or all-encompassing, which seems rather disingenuous.
The last line for direct assistance is at the county social services level. Those organizations don’t have the capability to scale. You’ll also be challenged as each county and state doesn’t necessarily want improve outcomes.