The Zoom R24 as the name says is a 24 channel digital recorder of which 8 can be used for recording at the same time. 6 channels can be equipped with phantom power, which for my personal use is more than enough. Furthermore it can be used as a Mackie mixer device on your DAW – I use Ardour on Ubuntu Studio and it works fine after a minimal configuration session. Speaking of computers, it can serve as an audio interface aswell and also as a reader for the integrated sd-card.
I personally don‘t use features like build in drum pads and so on, thus won‘t talk about them.