What is the irregular verb of talks?

Talk is not an irregular verb it is a regular verb because to make past tense you add -ed = talked.

Talks is the third person singular form of the regular verb talk. You use the third person singular form when the subject is he/she/it or a singular noun subject eg

He talks too much. She talks loud. It talks very well.

The doctor talks too much. The old man talks softly -- singular nouns subjects