To help differentiate areas and materials, NASA made the panorama (shown above) in "false color" which enhances certain elements. In the immediate foreground just left of center you can see a rocky outcrop that the vehicle had been investigating using its robotic arm in its final days. Helpfully, the image is annotated with other geologic details to give you a better sense of what you're looking at.
If you're curious why certain parts of the panorama remain in black and white, it's because the Rover was knocked out by the massive dust storm before it was able to capture those areas with all three color filters it typically used when shooting pics.
It's OK to be sad that to see Opportunity go, but the truth is that hearty space robot lived well beyond what was expected. Its mission was initially only meant to last 90 days, but it operated for a whopping 14 years. And, hey, its buddy Curiosity is still kicking out there and investigating all kinds of mysterious stuff.