Questions & Answers about Calea este lungă.
Because Romanian usually puts the definite article at the end of the noun.
- cale = way / path / road in an indefinite sense
- calea = the way / the path
So -a here is the feminine singular definite article attached to cale.
This is one of the big differences from English: Romanian says the road by changing the noun itself, not by putting a separate word like the in front.