This means “Salutations unto Śiva the auspicious one, unto Śivatara the one than whom none more auspicious can exist

Name of both chapters are Namakam (chapter five) and Chamakam (chapter seven) respectively.The mantra appears without the initial Om in the eighth hymn of Namakam(TS 4.5.8.1) as Namaḥ śivāya ca śivatarāya ca (Sanskrit: नमः शिवाय च शिवतराय च). Each chapter consist of eleven anuvaka or hymns.

Shri Rudram hymn is taken from two chapters in fourth book of Taittiriya Samhita (TS 4.5, 4.7) of Krishna Yajurveda. This mantra is present in the Shri Rudram hymn which is part of the Krishna Yajurveda. This Mantra appears as ‘Na’ ‘Ma’ ‘Śi’ ‘Vā’ and ‘Ya’ in the Shri Rudram hymn which is a part of the Krishna Yajurveda and also in the Rudrashtadhyayi which is a part of the Shukla Yajurveda. It is called Siva Panchakshara, or Shiva Panchakshara or simply Panchakshara meaning the “five-syllable” mantra (viz., excluding the Om) and is dedicated to Lord Shiva. Namah Shivaya means “O salutations to the auspicious one!”, or “adoration to Lord Shiva”, or “universal consciousness is one”. Om Namah Shivaya (Devanagari: ॐ नमः शिवाय IAST: Om Namaḥ Śivāya) is one of the most popular Hindu Mantra and the most important mantra in Shaivism.

Om namah shivaya benefits in hindi