This means that the last step is the president's signature and law entry into force. Once this happens, the Ministry of Foreign Affairs will send a note verbale to the depositary, the UN Secretary-General. The denunciation will take effect three months after the date of receipt of the notification by the Secretary-General.
What denunciation of the Optional Protocol to the International Covenant on Civil and Political Rights could lead to: read Natalia Matskevich’s commentary here (written in Russian).