where we use have and has?

Has is the third person singular present tense of have. This just means that it is used when you are speaking in the third person singular, i.e., with the pronouns he, she, and it. for ex:- He has a great idea. She has a car that we can borrow. The new iPhone is great; it has a bigger screen. John has a headache and doesn’t want to go out tonight. It’s not clear if the team has a policy prohibiting players from traveling when they are out with an injury.

Have is used with the first and second person singular present and plural tenses and the third person plural present tense. Again, in plain English, this just means you use have when you are speaking in the first and second person singular and third person plural, i.e., with the pronouns I, you, we, and they. for ex:- I have a great deal for you. Do you have any money? We have a new ride at the amusement park. They also have a wonderful gift shop.

If Subject is Third Person Singular like He, She, It and Singular names like Ram, Suresh , Jovika etc., we use has in present perfect tense as a auxillary verb or in simple present as a verb (possessive). Simple Present : He/She/It/Ram has a car. For the rest, we use 'Have'. I/We/They/You have a car. Present perfect: He/She/It/Ram has gone to market. I/We/They/You have gone to market. We use "Has" in present perfect tense in the same cases we use "is" is in present continuous.