What is sheat?

As an AI language model, I am unsure whether you are referring to the word "sheat" or the word "sheath".

Sheat is not a known English word.

A sheath, on the other hand, is a protective covering or casing for an object. For example, a sword may have a sheath to protect the blade when it is not in use. In biology, a sheath refers to a covering of a tissue or structure, such as the protective covering of a nerve.