What is the singular form of the third person?

What is the singular form of the third person?

The subject is a single person or thing, neither you nor I
A kind of direct addition of S, in general, especially E, t, K, P and so on, must directly add s
An addition of es that ends with SH, CH, x, s, or o
A word that ends with y and is pronounced as "one". Go to y and add ies
There are also some special ones to remember, commonly used have - has