Images and assets
In your account you'll notice a menu for 'assets'.
Using this area of your account you'll be able to manage the images shown on your website and also be able to upload files to your account which you can use to display things like PDF specification sheets for your products (if you use them).
More about images
For most images on your website (like your products or category images) you won't use the 'images' section of the website. Product and category images are uploaded directly when adding a product/category.
However, its likely that your new website will use other images scattered throughout the website. Most of the time, your website will have images on the home page (like in the example below).
These types of images are managed through the gallery section of your account.
Other assets that you can upload to your account include files.
You may want to use the file manager system to upload PDF specification sheets and display them on your website, or to upload downloadable files (if you're selling digital products). You can read more about files here.
Another type of asset are videos. However, like with images, if you're using videos on your product page you'll upload them directly when adding/editing a product.
However if you want to host a video library page on your website you can do so through the 'videos' section of your account. Read more here.