Paul is referring to the collection of money from the Corinthians for the believers in Jerusalem. Alternate translation: "who had encouraged your giving in the first place" (See: [[rc://en/ta/man/translate/figs-explicit]])
Titus was to help the Corinthians to complete the collection of money. Alternate translation: "to encourage you to finish collecting and giving your generous gift" (See: [[rc://en/ta/man/translate/figs-explicit]])