The Panchakshara (पञ्चाक्षर) literally means “five letters” in Sanskrit and refers to the five holy letters Na, Ma, Śi, Vā and Ya. This is prayer to Lord Siva and is associated with Siva’s Mantra , OM Namah Sivaya of which is also called the Panchakshari Mantra.
Here is a translation in Tamil of the epic Sthothram by Adi Sankaracharya
Prabhu's Ponder 