This is the 1430th most frequent Spanish word.
harán
"Harán" means "they will do" or "they will make" in English.
In this sentence, 'harán' is used as the third person plural future tense of 'hacer', meaning 'they will do'.
Ellos harán todo lo posible para ayudarte.
They will do everything possible to help you.
Here, 'harán' expresses a hypothetical result in the future contingent on the completion of a condition.
Si ellas estudian, harán un buen trabajo en el examen.
If they study, they will do a good job on the exam.
'Harán' indicates future action undertaken by the subject, 'mis padres', in relation to hosting and organizing an event.