Learn Turkish: Balayı için gidecekleri ülke çok uzak. - The country they will go to for the honeymoon is very far.

This uses the future relative participle taught in this lesson! It is made of the verb root git- (to go) + -ecek (future participle) + -leri (their). Literally, it acts like an adjective meaning "their future-going". Also, notice that the t in git- softens to d because it is followed by a vowel.

Where is the word for "to" in the Turkish sentence?

Turkish doesn't use extra words for "to" or "which" in these relative clauses. While in English we say "the country to which they will go" or "the country they will go to", Turkish simply links the participle directly to the noun. The directional "to" is naturally implied by the context of the destination (ülke) and the verb (gitmek).

Could gidecekleri also mean "the countries that he or she will go to"?

That is a great catch! The suffix -leri can sometimes be -ler (plural) + -i (his/her). However, because the noun here is ülke (singular country), -leri must represent the plural possessive "their". If the sentence meant "the countries he/she will go to", the plural marker would move to the noun, making it gideceği ülkeler.

Why does the word for honeymoon, balayı, end in -ı?