Complex sentence: The twin deficits theory is the contention that there is a strong link between a current account deficit and a government budget deficit, in the sense that a large budget deficit leads to a large current account deficit.
Split into simpler sentences: The twin deficits hypothesis is a concept from macroeconomics that contends that there is a strong link between a national economy's current account balance and its government budget balance. As an example, it is hypothesized that a large budget deficit leads to a large current account deficit.