The word "But" connects this verse to the previous verse about the hypocrisy of the Pharisees. (See: [[rc://en/ta/man/translate/writing-connectingwords]])
"everything that is hidden will be shown." This can be stated in active form. Alternate translation: "people will find out about everything that people do secretly" (See: [[rc://en/ta/man/translate/figs-activepassive]])
This means the same thing as the first part of the sentence in order to emphasize its truth. It can also be stated in active form. Alternate translation: "people will learn about everything that others try to hide" (See: [[rc://en/ta/man/translate/figs-parallelism]] and [[rc://en/ta/man/translate/figs-activepassive]])