Learn Turkish: Yeni projenin kentsel bir dönüşüm olduğunu duyduk. - We heard that the new project is an urban transformation.

In Turkish, to say "that something is a [noun]", we use the helper verb olmak (to be/become). We take the root ol-, add the factive participle -duk, then a possessive ending to show what is being described (here, -u for "it"), and finally a case marker. So dönüşüm olduğunu literally means "its being a transformation".

Why is the subject projenin in the genitive case instead of just proje?

When you form a "that" clause using -dık or -ecek, the subject of that clause takes the genitive case. Since "the new project" is the subject of the embedded clause, it becomes yeni projenin. This genitive subject links grammatically to the possessive suffix on olduğ-u-nu (the project's being).

Why does olduğunu end with the accusative case marker -nu?

The entire clause Yeni projenin kentsel bir dönüşüm olduğu (that the new project is an urban transformation) acts as the direct object of the main verb duymak (to hear). Because you are hearing a specific, defined fact, the clause requires the accusative case. The -n- is a buffer letter between the possessive -u and the accusative -u.

How is the adjective kentsel (urban) formed?