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When setting up a dual boot system, you will have one existing NTFS partition for Windows and will be resizing it to add an ext4 partition and a swap partition for Linux. NTFS, ext4, and swap are just names for the types of partitions.
When you install Ubuntu, Windows will not be able to recognize the partition (the part of the disk) that Ubuntu is installed on. Windows will recognize that Ubuntu partitions exist, but will not be able to tell you what type they are, or read and write data to them. There are a couple ways you can access Linux partitions from Windows, like with the free programs Explore2fs, DiskInternals Linux Reader, or the Ext2 File System for Windows.
Ubuntu, however, will recognize your Windows partition, and you will be able to "mount" it, read and write data to it. Upon login, you will see a link on your desktop to access your Windows partition, and there will be a sidebar entry in the file manager for easy access. Upon opening it, you can explore much of the user data in the "Users" folder.
Upon boot, you will see a menu with the option to boot from Linux or Windows, with a couple of other options (which happen to be on your Linux partition) for diagnostic purposes.
In Ubuntu, you can install GParted. This will allow you to view a simple visualization of the layout of your disk partitions, and has quite a few tools for manipulating them as well. You will only want to manipulate your partitions when making more free space, installing other operating systems, or doing other system-related tasks.
Good luck with Ubuntu! I hope your experience is a good one. It's great, here in the Linux world.
