What is Moksha (ultimate liberation) ? What happens to a soul after Moksha?

Mukti or the Supreme Goal means that the soul, being freed from the cycle of birth and death, attain an immortal body.

Mukti or ultimate salvation means being freed from the bondage of the soul cycle and attaining an immortal body.
Every living being wanders in 84 lakh yonis and is born as a human being, animal, bird, insect, aquatic creature, or small creature.

Human birth is the only birth to attain salvation, salvation cannot be attained in any other birth.

A living being has human birth only to attain salvation by doing Bhakti(love, surrender, and service).

Bhakti is the only easy path by which a human can attain ultimate salvation (Vaikunth Lok).

When a living being gets salvation, at the time of death, the representatives of Lord Mahavishnu come and take the liberated soul on a journey to Vaikunth Lok in a golden plane(divine plane).

Where a human being gets a divine body. Which is also called Amar Sharir(no death). Which never decays, never gets old, never feels hungry, never feels thirsty, never feels sad, never has any disease, where a human always remains young.

Where a human always lives in bliss with Lord Shri Krishna, Mother Radha Rani, and their devotees. That divine body never gets destroyed even at the time of Brahma Pralaya(destruction of the universe).