This is the 4437th most frequent German word.
internationaler
"Internationaler" means "international" (adjective) or "international player/representative" (noun, when referring to a person).
The word 'internationale' here modifies 'Konferenz', denoting that the conference pertains to or involves multiple nations.
Wir besuchten eine internationale Konferenz.
We attended an international conference.
The term 'internationale' qualifies 'Flughafen', indicating that the airport handles flights between different countries.
Der internationale Flughafen ist gut erreichbar.
The international airport is easily accessible.
The phrase 'internationale Unternehmen' specifies a company that operates across national borders.