Learn Turkish: Bu adamlar kim? - Who are these men?

In Turkish, suffixes change to match the vowels in the word they attach to. This is called 2-way vowel harmony. We look at the last vowel of the word adam, which is a. Because a is a back vowel, we use the back vowel plural suffix -lar. If the last vowel were a front vowel like e or i, we would use -ler instead.

The English translation says "these men", but bu means "this". Shouldn't we use the plural word bunlar?

No, this is an important rule in Turkish! When a noun is already pluralized (like adamlar), the pointing word or adjective in front of it must stay singular. So, "these men" is always bu adamlar, never bunlar adamlar. You only use the plural bunlar when the noun is dropped entirely, like in Bunlar kim? (Who are these?).

Since "men" is plural, can we make the question word plural too, like kimler?

Yes, you can say Bu adamlar kimler?, but it is completely optional. Since adamlar already tells us we are talking about multiple people, just saying kim is perfectly clear and very common in everyday speech.

Where is the word for "are" in this sentence?