There are eight 12C interfaces on one expander with eight bi-directional transfer switches that can be controlled via the 12C bus.
This means: after 1 expander is converted, you can connect 8 devices with the same address on the same l2C port and use them normally. This expander address is changeable and can be set within 0×70~0×77 according to your needs.
Theoretically, you can cascade 8 expanders within the address of 0×70~0×77, and each expander can connect 8 devices with the same address, which makes it possible to connect 64 devices with the same address to the same 12C port and use them normally.