This is the 479th most frequent Estonian word.
rapla
"Rapla" is a proper noun and refers to a town and municipality in Estonia.
Here 'Rapla' is used again as a proper noun, specifying the train station located in the town Rapla.
Tulen homme Rapla rongijaamast ära.
I will leave the Rapla train station tomorrow.
In this sentence, 'Rapla' is used as a proper noun, denoting the name of a town.
Rapla on väike linn Eestis.
Rapla is a small town in Estonia.
In this case, 'Rapla' is used as an adjective referring to something characteristic or associated with the town Rapla.