concluding episode; final volume; concluding part
Used for the final installment of a serialized work such as a TV series, novel series, or film series. Often implies a planned conclusion.
The concluding episode of this drama will be broadcast next month.
The final volume of the trilogy has finally been released.
完結 is the noun meaning 'conclusion' or 'completion'. 完結編 specifically refers to the concluding part or volume of a series.
Compound of 完結 (kanketsu, 'conclusion') + 編 (hen, 'volume' or 'chapter'). The reading is standard on'yomi.