One of the key functions of the final paragraph of an article or other writing is to remind readers, in a concluding sentence, of the theme or premise you laid out at the beginning by restating that premise or theme. For example, if your theme or premise stated that you planned to write about ways people should take care of their dogs, remind the readers of this in that final concluding paragraph. There might be 500 to several thousand words between that first paragraph when you first stated the theme of the article and that final paragraph, with several experiences or information illustrating your premise in between.
A second key function of a concluding paragraph is, in a couple of sentences, to summarize the points you made in your writing. For an article on caring for dogs, summarize information shared on dogs' paws being burned by hot sidewalks or even dying on hikes with their owners: "Dogs, like people, do not deal well with either cold or heat and must be protected even on walks." If you shared information on watching out for outside dogs, summarize with: "On hot days, provide a lots of drinking water, a pool for splashing and shade. Better yet, bring the dog indoors until the weather cools down."
A concluding sentence brings everything you've written into a final push to reach the reader and is the third key function of a concluding paragraph. You want the readers to respond to what you've written. If you wrote about a political situation, encourage readers to write their senators. If you wrote about the homeless, reiterate how readers may help. If your reason for writing is to help dog owners better understand the needs of their animals and be better prepared to protect them from negative weather conditions, make this point in your concluding sentence: "Good dog owners show they care about their dogs when they take the time to protect their beloved animals both in hot and cold weather."
Whatever the premise or theme of your article, however much information you choose to include between the beginning and ending paragraphs, the whole article falls if your concluding paragraph doesn't remind readers of the purpose of the article, refresh their minds by summarizing points and elicit a response with the final sentence. The concluding paragraph is about take-away value. If readers reach the end of your piece and find no wrap-up, they will feel cheated and frustrated and wonder why they spent the time to read a piece with no ending, no real conclusion and no take-away value.