could you please tell me which word to use in between HAVE and HAS in the following sentence? you are the one who have to understand or you are the one who has to understand.

I think "You are the one who has to understand." is correct . "Has" is use when the subject is singular and "Have" is use when the subject is plural. Here the subject (you) is singular . So I put "has" in this sentence.

in these sentences if you are using singular noun or a pronoun then there 'has' will be used and on the other hand if you are using plural noun or pronoun in the sentence then you need to use the helping verb 'have"