1)For those things that are alive and live like animals and humans, you should use "an"("a" is
pronounced like a in "art")
but if you use"ha". that would be correct,too.
2)for those things which are object and don't have life and for Abstract Noun you should use"ha":
ex:Ketab ha (books)
sang ha (rocks)
farsh ha (carpets)
ghaza ha (foods)
gham ha (sorrows)
3)For plants and herbs you can use both"ha" and "an"
nahal ha (saplings)/nahalan(saplings)
4)Parts of body which are pair like eyes/hands can become plural by "ha" and "an"
abroo ha/abrovan(eyebrows)("abrovan is really literary and we don't use it in daily life)
zanoo ha/zanovan(knees)("zanovan is the same as abrovan and is not used in conversation)
angosht ha/ angoshtan(fingers)
***for "foots" and "ears" we just use "ha":