This is the 454th most frequent Turkish word.
merkezi
"Merkezi" means "central" in English.
Here, 'merkezi' (center) functions as a noun modified by 'Türkçe öğrenim' (Turkish learning), describing a location used for learning Turkish.
Türkçe öğrenim merkezi çok kalabalık.
The Turkish learning center is very crowded.
In this context, 'merkezi olarak' (centrally) acts as an adverbial phrase derived from 'merkezi' (central), indicating the manner in which the management is performed.
Projeyi merkezi olarak yönetiyoruz.
We manage the project centrally.
Here, 'merkezi' (central) is used as an adjective modifying 'bir yaklaşım' (an approach), describing the nature of the approach as central.