。
There are limits to everything.
Literal
Things [location-に] [topic-は] limit [quotative-という] thing [subject-が] exist.
限界というものがある means 'there exists a thing called a limit.' ~というもの adds weight or formality to the noun — not just 'a limit' but 'the concept of a limit.' に marks the location ('in things'), and the topic は contrasts with what other domains might lack.