When using the present tense (with 'to have' as the main verb), or the present perfect tense (with 'to have' as the auxiliary verb), 'has' is used only in the third person singular-- that is, when the subject is a single entity that is not you or I: he, she, it, John, the Eiffel Tower, etc.
I have a headache.
You have a headache.
She/ he/ it/ John/ the Eiffel Tower has a headache.
We have headaches.
You all have headaches.
They have headaches.
I have never eaten locusts.
You have never eaten locusts.
She/he/it/John/the Eiffel Tower has never eaten locusts.
We have never eaten locusts.
You all have never eaten locusts.
They have never eaten locusts.
haveis used with
hasis used with
The countable and uncountable nouns sometimes can create lots of confusion as to whether to use singular (has) or plural (have).
Police, as strange as it might seem, is referred to as plural noun and therefore takes
have as in:
The police have arrested a suspect in connection to the recent robberies in this neighborhood.
Here are some more examples:
She has just quit her job.
I have hired a new secretary to replace her.
I have to pay her more money though.
You have to train her as to what she has to do.
The scissors have dull edges.
My glasses have scratches on them
My trousers have holes on them