The device information page contains basic information on the selected device. When the page is accessed, it will try to read the JTAG (or device) signature from the connected device.
In the upper part of the dialog, you can see the device name, its signature, the JTAG part identification number, and the device revision (extracted from the JTAG signature).
You can see the device variants and characteristics in the lower part of the dialog as acceptable voltage range, followed by maximum operating clock speed and the sizes of on-chip memories that can be used.
The two links on the bottom of the dialog offer you to see slightly more detailed device information in the purchase catalog online or to download a complete data sheet of the target device.