Yes, it can be confusing at start.
Short explanation:
When the PSU is current limiting, it is in CC mode. Otherwise it is in CV mode.
Somewhat longer explanation:
CV and CC are the results of a maximum Voltage and a maximum Current that you have set, and the load that you connect to the PSU.
Suppose you set the PSU to 5V and 1A. Those are the maximums. The PSU will provide a maximum of 5V, and a maximum of 1A (*)
If you connect nothing, there will be no current drawn, and the PSU can supply up to the maximum voltage: 5V. The PSU will be limiting to the maximum voltage set, and will be in Constant Voltage mode: CV.
If you short circuit, the maximum current will be drawn: 1A. The PSU will be limiting to the maximum current set, and will be in Constant Current mode: CC.
through V = I * R, you can see that if you connect 5 ohms, you will get both 5V and 1A. It will be on the switching point between CV and CC.
Anything over 5 ohms, and you will still get 5V (the maximum), but a lower current than 1A. The PSU will be in CV mode.
Anything under 5 ohms, and you will get 1A (the maximum), but a lower voltage than 5V. The PSU will be in CC mode.
(*): ...in steady state. In some circumstances, and during very small periods these maximums may be exceeded, but I imagine that is not your preoccupation right now.