"Is she a farmer? She is not."
Translation:An feirmeoir í? Ní hea.
To supplement SteffanieS’ reply, ea is a generic pronoun that’s only used with the copula in modern Irish. The responses is ea and ní hea (ní causes an immediately following pronoun that begins with a vowel to be preceded with an H) can be given to classificational copular questions (i.e. those copular questions that have an indefinite complement) in the present tense, in the same way that English would generically use “yes” and “no”, or (in the particular case of this question) “she is” and “she isn’t” respectively.
I will answer while waiting for Those Who Know to respond. This seems related to "An ea?" which meant, "Is it?" It seems to literally translate to, "It is not," which is a fancy way to say, No, since there is no single word to mean No in Irish. Now, awaiting the real answer....