The Fluidic Compressor is used to compress fluids and put them into Canisters for storage and transportation in item form. To do that it uses power and liquids. It can also extract the fluids out of the Canisters again, to do that it doesn't need any power.
On the left of the GUI are the 2 buttons to toggle the mode the machine works is. The top one puts it in "fill" mode, the bottom one in "empty" mode. The slot in the middle is for the canister it is working on (with progress bar below it). Once it is done filling or emptying the current canister, it will put it in the output slot.
Automating the Fluidic Compressor
It can be automated using hoppers or pipes, all sides can be used both for input and output.