You might like to think of your body paragraphs as being mini-essays in terms of their structure. That is, you still need to introduce them and conclude them in the same way that you introduce and conclude your essay as a whole. Because of this, the first and last sentence of your body paragraphs are very important in terms of introducing and concluding each point that you make before you move on to the next one.
I have just answered your other question about how to start a body paragraph, so I will use the same example to explain how you should end a body paragraph. If you are writing an essay on The Adventures of Huckleberry Finn and the themes that this novel contains, your paragraph looking at the theme of the hypocrisy of Christianity should end by briefly summarising the importance of this theme and rounding off this paragraph before you move on to the next theme that you are going to look at. How you conclude this paragraph depends a lot on what you have actually said, but this should give you an example:
Through the series of characters that Huck interacts with and how so many of them are overtly Christian whilst practising habits and behaviours that clearly contradict their religious belief, Mark Twain therefore presents us with the hypocrisy that is inherent in so much of Christianity.
This clearly highlights the main theme that you have been talking about whilst also effectively concluding this paragraph before you carry on to the next paragraph.