Breakdown of Est-ce qu'ils iront à la filiale pour six mois ?
ils
they (masculine/mixed)
pour
for
à
at / to / in (general locations) / about (what one thinks about / reacts to)
est-ce que
is it that / do / does (question marker)
Questions & Answers about Est-ce qu'ils iront à la filiale pour six mois ?
Why do we use pour instead of pendant to say "for six months" here?
This is the core rule for expressing future intended duration! When an action involves going somewhere or starting something with a planned duration for the future, French uses pour. If you were talking about a completed past action or a general ongoing duration, you would use pendant (for example, Ils y sont allés pendant six mois meaning "They went there for six months").
Is filiale a false friend?
Yes, in this context! While French does have the adjective filial(e) meaning the same as the English "filial" (relating to a son or daughter), as a noun une filiale is a business term meaning a "subsidiary" (a company controlled by a parent company). Another similar business word you might see is une succursale, which means a "branch".
What verb is iront?
Iront is the verb aller (to go) conjugated in the futur simple for ils/elles. The future stem for aller is highly irregular (ir-), to which you add the standard future endings (-ai, -as, -a, -ons, -ez, -ont).