How do I hide and display Blocks on Specific Devices?

You can select what devices each block can be shown on. The devices are split up as follows -

Mobile
Tablet
Desktop

After selecting a block, you will see the Devices setting in the menu under the Block tab. When a device is selected, it will be highlighted with a white underline. For example the block in the above screenshot will only be shown on mobile devices. You can turn each one on and off until you have the desired layout.

It is important to check the layout of your pages on all devices, as some content may not be suitable for all.