Here "understanding" refers to understanding about God. This can be stated clearly. AT: "as you learn and understand more about what pleases God" (See: [[rc://en/ta/man/translate/figs-explicit]])
The words "sincere" and "without offense" mean basically the same thing. Paul combines them to emphasize moral purity. AT: "completely blameless" (See: [[rc://en/ta/man/translate/figs-doublet]])
Paul is speaking of the believers as if they were containers that could be filled with fruit. AT: "This is also so that Jesus Christ may cause you to obey God more and more" (See: [[rc://en/ta/man/translate/figs-activepassive]] and [[rc://en/ta/man/translate/figs-metaphor]])
The good deeds of a believer whom God has declared good please God as does the way fruit growing on a tree is sweet to those who eat it. AT: "able to please God and other people by the way you live now that God has forgiven your sins" (See: [[rc://en/ta/man/translate/figs-metaphor]])
Possible meanings are 1) "Then other people will see how you honor God" or 2) "Then people will praise and give honor to God because of the good things they see you do." These alternate translations would require a new sentence.