I know panchakshari mantra, But want to know clear explanation, What is intent of panchakshari mantra?
Literal meaning of "Namah Shivaya" is "adoration to Shiva". "Namah Shivaya" also represents panchabhutas(5 elements). It is well explained by Bodhinatha Veylanswami ji in his book Path to Siva. I'll quote that part here:
Namaḥ Śivāya is the most famous and holy of Saivite mantras, chanted daily by millions of devotees. Namaḥ Śivāya means “adoration to Siva” and appears in the Yajur Veda in the famous Shri Rudram hymn to Siva. It is known as the Panchakshara, or “five letters.” Each syllable has a meaning. Na is the Lord’s concealing grace and Ma is the world. Śi stands for Siva, Vā is His revealing grace, and Ya is the soul. The five letters also represent the five elements. Na is earth, Ma is water, Śi is fire, Vā is air, and Ya is ether, or akasa. This mantra is repeated verbally or mentally, drawing the mind in upon itself to cognize Lord Siva’s infinite, all-pervasive presence. It is freely sung and chanted by everyone, but it is most powerful when given by one’s guru. Gurudeva advised, “When life becomes difficult or strained, say to yourself ‘Śiva Śiva’ or ‘Aum Śivāya’ or ‘Namaḥ Śivāya.’ Mentally put it all at His feet.”