Reality, according to Vedas is a Principle.
It is called Brahman.
It is beyond words,thoughts .
It is indescribable,Avaktavya.
However worship of God’s is also recommended in Hinduism and it is called Saguna Aradhana,while meditating on the Abstract is called Nirguna, Beyond Attributes, Aradhana.
To reach this level is not easy for all.
Therefore worship of Gods is recommended in the form of Idols.
What is indescribable, Avaktavya, becomes Vyaktha, Describable when worships as God of Names and Forms in the form of Idols.
Some of these Idols are called Self Manifested or Swambhu.
There are Eight Self Manifested Idols of Lord Vishnu in Eight Sacred places.
These are called Vyaktha Kshetras,that is where Lord Vishnu makes Himself available as Idol and thus becomes Describable.
There are also called Astakshara Temples as they represent the eight letters of Vishnu’s Sacred Name,
Om Namo Narayanaya.
There also Dwadasa nama temples,after Vishnu’s twelve aksharas.
Om Namo Bhagavathe Vasudevaya.
Srirangam Venkatadrischa SrimushNam Totaparvatam
Salagramam Pushkaramcha NaranarayaNAshramam
Naimisham Cheti ME SthananyasoU Mukthi PradhAnivai
YetusvashtAksharaIkAka: VarNamUrthir VasAmyaham
TishtAmi KrishNa KshEtrE puNya SapthakOgatha:
AshtAksharasya Mantrasya SarvAkshara Maya SadA
In this verse Lord Narayana points out that the eight
Swayam Vyakta Kshetrams of Srirangam, Tirupathi, SrimushNam,
Vanamamalai, Salagramam, Badri,and NaimisharaNyam,Pushkar
grant liberation to those who visit the place.
The Lord as the Archa Murthy at each of these Kshetrams
signifies one Aksharam of his Ashtakshara Mantram.