Strictly speaking, the headline is misleading, and doesn't agree with the article.
The proposed law says no one under 25 can be charged with Murder 1, premeditated murder. This means it is either Murder 2 (unplanned, intentional killing) is allowable. There are also Reckless Homicide or Manslaughter, and Criminally Negligent Homicide. The last two seem almost the same, but I found a source that says Recklessness is when you know you are taking a risk, and yet it results in a death. Criminal negligence is when you should have known better, and your action resulted in a death.
All four of these are felonies. The article is saying that under 25 year olds could be charged at most with the lower three. I assume this is because a younger person planning a murder and carrying it out is assumed to not fully understand this is wrong, or cannot be expected to control themselves.
It's nonsense of course. Everybody knows murder is wrong. Sometimes very young children commit murder, and you could argue a person that young lacks the impulse control to be held fully culpable for their actions. However, there's no way that approach should be applied up to age 25. Anyone over their early teens should be held accountable for premeditated murder.
In any case, as the picture shows, the real goal is to reduce charges for blacks.