Pardes and Pardesi are common words of Hindi which are not very highly used in the daily language, especially in written, but are way too common in songs and poetry. Pardes is made of par (other) and des (country) and thus simply means a foreign country.
Pardesi, which is derived from Pardes means a foreigner.
Still, in contexts of various poems and songs, the words do not particularly express a different nationality and anyone who lives 'away,' can be called a Pardesi. :)