Closing/concluding sentence = fecho (de uma carta, por exemplo)
Trata-se da última frase de um texto. Ex.:
There are three reasons why Canada is one of the best countries in the world. First, Canada has an excellent health care system. All Canadians have access to medical services at a reasonable price. Second, Canada has a high standard of education. Students are taught by well-trained teachers and are encouraged to continue studying at university. Finally, Canada's cities are clean and efficiently managed. Canadian cities have many parks and lots of space for people to live. As a result, Canada is a desirable place to live.
A frase em itálico, que aparece por último, conclui, fecha ou encerra o texto. Portanto, temos aí uma "closing" ou "concluding sentence".