The 12 Rawatib are the confirmed Sunnah prayers the Prophet ﷺ prayed daily: 2 before Fajr, 4 before Dhuhr, 2 after Dhuhr, 2 after Maghrib, and 2 after Isha. These are shown as small annotations next to each fard prayer above.
The timed voluntary prayers — Ishraq, Duha, Tahajjud, and Witr — are shown as separate rows with their calculated times for your location. These are among the most rewarded optional prayers in Islam.
Duha: "Charity is due upon every joint of a person. Every day the sun rises, it is charity to judge justly between two people… and two rak'at of Duha suffice for all of that." SAHIH MUSLIM 720