Yes, you are looking at a hydronic type, diesel-fired heater. This amounts to the equivalent of a boiler in a house - that is, it uses a diesel fire to heat water, which then is piped (usually via hoses) to your domestic water heater, and also can be piped to small radiators (usually with a small 12 V fan behind them) in order to heat your cabin, head, vee berth, etc.
I am considering one of these for my boat as well. Another maker is Webasto.
The unit that you are looking at is made by Espar, and these are used not only for boats, but big rig trucks, in order to heat the sleeper cabin as well as to keep the diesel engine warm when shut down overnight. Sometimes you can get better prices on these units via a truck supply company vs. the always-more-money "marine" version (same thing)!
Any of these units will require a separate fuel supply pump (taking suction from your main engine diesel tank), and a small exhaust line (insulated, corrugated stainless steel) usually leading to a through fitting in the boat's transom.
Good luck, and let us know how your project turns out!