The conclusion section is the climax of the story. In the three-act narrative structure, the aims of the main character are usually given at the end of the first act, once the world and situation has been introduced. It’s then up to the main character to overcome the obstacles thrown up in the second act in order to achieve their goals. Once the battle is won, the hero can bask in the glory. Similarly in scientific writing, after the large results and discussion sections, you need to take stock and reflect on what you’ve actually managed to achieve.
The conclusion section is fairly easy to write as it simply mirrors your aims. If your aim was to use [method x] to test [condition y] and your results show that it worked and you know what the answer is, then you just write that out in the conclusion. “We tested [this] using [that] and found that…”. It follows for all your aims. Something to remember is that in the aims section I said that you must be specific, and here’s where it pays off. By being specific in your aims, you can now be equally specific in your conclusions.
However, (and you knew there was going to be a trap to avoid!) do not be tempted to explain why in your conclusion. The conclusion is a statement of fact. It is a fact that your results say a certain thing. You tested some part of reality and now you know how it behaves under those conditions. You did not test your speculation, so it is not fact and therefore does not belong in the conclusion. Speculation and explanation are for the discussion, not the conclusion section.
Likewise, in Star Wars, it is a fact that Luke and the rebels have managed to pull off the daring raid that resulted in the destruction of the Death Star. The film doesn’t waste time re-examining the whys and hows of the feat. Tension over, it moves straight into celebrating the fact.