In practical terms, it means that if there had not been a provision allowing for concurrent jurisdictions, only the provinces would be able to prosecute. So you would have either the RCMP or provincial law enforcement laying charges, but only the provinces would be prosecuting.
With concurrent jurisdiction, it does mean that the federal prosecution service will be able to prosecute these offences as well. So practically speaking, it's likely that the RCMP will lay charges and the federal prosecution service will prosecute in many cases, and in other cases, either form of law enforcement will lay a charge and then the provincial prosecutors will prosecute. It really will depend on the area.