"El pollo" is the subject. "El pollo" is a third person, singular subject, so it needs a verb in third person, singular form. The form "somos" is the first person, plural form (we), so it is incorrect. The correct third person, singular form is "es".
Incorrect: <span>“El pollo somos delicioso.” Correct: </span><span>“El pollo es delicioso.”</span>