Learn Turkish: Boş kutular kilerde saklanacak. - The empty boxes will be kept in the pantry.

The root verb is saklamak (to keep, to hide). Because the root sakla- ends in a vowel, the passive suffix is simply -n, giving us saklan- (to be kept). Finally, the future tense suffix -acak is added to make saklanacak (will be kept).

Doesn't saklanmak also mean "to hide oneself"? How do we know it's passive here?

You're right! The -n suffix is also used to form reflexive verbs (where the subject does the action to itself), so saklanmak often means "to hide oneself". However, since empty boxes (boş kutular) can't hide themselves, context tells us this is the passive voice meaning "to be kept" or "to be stored".

Since kutular (boxes) is plural, why isn't the verb plural (saklanacaklar)?

In Turkish, when the subject of a sentence is plural but non-human (like boxes, animals, or ideas), the verb is almost always left in the singular form. That's why it is saklanacak instead of saklanacaklar.

What kind of room is a kiler?