A Mult is nothing more than two or more jacks combined together so if you put a plug in one jack the other jack also has the signal on it. -Think of it as an AC plugin strip for audio. One in - multiple outs.
Remember that you can take one output and take it to multiple inputs but you cannot take multiple outputs and plug them into a Mult as you will probably blow the outputs of the gear you are trying to Mult.
Also, depending on the gear one output can feed multiple inputs but each piece of gear has an input impedance and if you go lower than the output impedance of the device you are feeling from (by paralleling multiple low impedence inputs across it) you can cause distortion and a screwed up frequency response - so know your gear specs before plugging it all in.