In traditional Islamic practice (accepted by many Sunni and Shia schools, though debated by Salafis), Tawassul means asking a righteous person to pray to God on your behalf. Believers call upon "Ya Syeda Shodai" as a means of drawing closer to Allah. They believe Fatima, given her impeccable purity (Tahira) and proximity to the Prophet, holds a high rank of intercession on the Day of Judgment.
The phrase (O Leader of the Martyrs) is a title of immense reverence in Islamic tradition, most notably referring to Imam Hussain ibn Ali (the grandson of Prophet Muhammad) or Hamza ibn Abd al-Muttalib (the Prophet's uncle). ya syeda shodai