Learn Turkish: Bu yol çok uzun. - This road is very long.

Turkish doesn't have a direct equivalent for the verb "to be" (am/is/are) in the present tense. For "he/she/it/this", you often just place the subject and the adjective next to each other. So, Bu yol çok uzun literally translates to "This road very long", and the "is" is naturally understood by the listener.

Why does bu mean "this" here, but in other sentences it can mean "this is"?

Bu simply means "this". When it is placed right before a noun like yol (road), they group together to mean "this road". If bu was standing on its own as the subject without a noun directly after it, as in the sentence Bu çok uzun, it would translate as "This is very long".

Does çok mean "very" or "much"?

It can mean both depending on the word that follows it! When çok is placed before an adjective like uzun (long), it means "very" (very long). If you use it with a noun or an action, it means "much", "many", or "a lot".

Is "road" the only meaning of the word yol?

While it means "road" here, yol is a very common and flexible word that can also mean "way", "path", or "method". Because of this, the sentence could also be translated as "This way is very long".