What is the correct name for the Companion: Sari or Sariah, and which of them is more accurate? And what is the biography of this Companion?

There is no Companion named Sari. Perhaps the questioner means Sariya ibn Zunaim al-Du'ali, who was a Companion. Sariya was a thief in the pre-Islamic era (Jahiliyyah), then he embraced Islam and his Islam became good. Umar appointed him as a commander over an army in Persia in the year 23 AH. During his Friday sermon, Umar had a premonition that the army was facing danger, so he called out: "O Sariya, the mountain, the mountain!" Sariya heard it and withdrew his army to the mountain, and they achieved victory. This is a well-established miracle for Umar and his soldiers. The army gained much spoils, but Umar refused to take a share for himself and ordered it to be returned to the Muslims.