If your AMD Processor ends in a letter like "G or GE" for Desktop processor then it is a APU or processor with Integrated Graphics.
Radeon Graphics is the name of the AMD Integrated Graphics for the newer APUs.
Yes you can later on upgrade by installing a separate GPU card as long as it has the correct PCIe slot, PSU connections, and fits in your Computer case and powerful enough PSU to run the computer with the new GPU card.
In BIOS Settings it is normally set to make your separate GPU Card the Main Display Adapter automatically when you install it in your computer even if you have a Integrated Graphics processor.