I/O interfaces are bank-wise configurable. The maximum number of I/O pins per bank is 26. The bottom row of the each GPIO Bank table displays the available number of GPIO's for each bank. After some GPIO configuration it shows 0, which signifies all the I/Os of the particular bank is already used. If configured, I/Os exceeds the I/Os available in the bank, it will give a DRC, and you should use the GPIOs in other banks.
Figure 1. GPIOs available after Selection of Interfaces
You can configure GPIO bank voltage from I/O banks.
Figure 2. Voltage Selections
Note: Power section in the above table only
reports power on VCCO_50x IO's and I/O power in VCC_PSLP is
not reported in this table.