This is the 932nd most frequent Ukrainian word.
кордоном
"Кордоном" means "abroad" or "beyond the border" in English.
Here, 'кордоном' refers to 'abroad' in the sense of being outside the country.
Він працює за кордоном.
He works abroad.
In this usage, 'кордоном' is related to a border line separating territories.
Кордон між країнами був відчинений.
The border between the countries was open.
Here, 'кордон' in 'за кордон' implies travel beyond the national border.