This can be used to rotate the image for an interesting effect, or more commonly to correct the image if it is at a slight angle.
If your photo is too bright or dark, you can adjust the brightness in order to get a well-balanced image.
You can take photos within the app. This allows you to do everything from capturing the image to editing all within one app, instead of having to import an image taken with another camera app.
Adjusting the contrast affects the difference between light and dark areas of the image. You can fine tune it to meet your needs, such as increasing the contrast to make your subject stand out more.
Saturation refers to the intensity of colors. It is measured on a scale ranging from 0% (black and white) to 100% (pure colors) at a constant level of brightness. Images with high levels of saturation have vivid colors, while unsaturated images appear greyish.
With a self-timer you can set an amount of time to pass before the picture is taken. This allows you to be in the picture yourself and is great for taking photos with friends.
It allows you to take multiple photos capturing different parts of the scene, and then joins them together into a single photo.
A timelapse shows a long passage of time sped up. A series of photographs taken from the same position over a long period is joined together to create a short video. It is great way to capture things like the setting sun, or clouds moving across the sky.