I think this bill is very straightforward. Anyone convicted of murder after this point will not be eligible for what is known as the faint hope clause after 15 years. Their first opportunity for parole eligibility would be at 25 years.
In addition, with the other bill you've referenced, if an individual is convicted of two, three, or multiple murders, the judge then will have the discretion to have their parole ineligibility in consecutive terms. As I think Mr. Comartin pointed out, you could be waiting for 50 years if you start killing more than one person.