hay/está

Question

So, "hay" is used for both singular and plural? And not "han bares in mi varrio"? Can "ha" be used in such a case?

Answer

Yes, there is only one form, "hay" as the impersonal "there is/there are". The other forms of the verb "haber" that you are referring to are those used for each subject, which are the first part of the perfect tense:

Yo he ido al mercado. (I have gone to the market.)
Tú has ido al mercado. (you have gone to the market.)
Él/ella ha ido al mercado. (he/she has gone to the market.)
Nosotros hemos ido al mercado. (we have gone to the market.)
Vosotros habéis ido al mercado. (you [pl] have gone to the market.)
Ellos han ido al mercado. (they have gone to the market.)

Saludos
Inma