If your '10A' supply switches into a constant-current mode like a typical lab bench supply, and it is set to exactly 10A for the current limit, then it will give you 5V out with a 0.5 ohm resistor. When you first connect it, it might give you a big spike because of internal capacitance.
It will also get extremely hot (both the resistor and the power supply) and is a 5V supply with exactly 0% efficiency. You could load it with say 500mA and the voltage would only drop 5%, at which point you might have 80W being consumed to produce an output of 2.5W so our efficiency improves to a whopping 3%.
However most supplies are not like that, and will limit at considerably more than their rating for period of time, so you might see it throbbing at 8V or something of that ilk. Thus promptly destroying anything that was limited to 5 or 6V and connected to the output, of course.
The rating of a power supply is what you are allowed to draw long term and only loosely related to what actually happens when you apply a load.