Complex sentence: Antonio agrees, but since he is cash-poor--his ships and merchandise are busy at sea--he promises to cover a bond if Bassanio can find a lender, so Bassanio turns to the Jewish moneylender Shylock and names Antonio as the loan's guarantor.
Split into simpler sentences: Antonio agrees, but since he is low in cash--his ships and merchandise are busy at sea--he promises to cover a bond if Bassanio can find a lender. So Bassanio turns to the Jewish moneylender Shylock and names Antonio as the loan's guarantor.