What is CV & CC in power supplies?
They are acronyms and stand for "Constant Voltage" or "Constant Current".

They usually are associated with a LED or an indicator of some kind, as you suggest. When you use a power supply you usually set the desired voltage and the maximum current. When you connect the load two things can happen:


The load requires more current than the maximum you set
The load requires at most the maximum current you set


In the first case the PSU become a current source: the current is limited to what you set and voltage drops accordingly, that's CC for you. In the second case what is costant is the voltage, so that's CV.

As an example, consider this case: you set the voltage at 10V and set the maximum current at 1A, then you hook up a load that is over \$10\Omega\$ . As you know that requires at most 1A, so the voltage is constant while the current can vary between 0A and 1A. If you then hook up a lower impedance load it would require a higher current, but now the current protection kicks in so the current is limited to 1A, and it is constant, while voltage varies between 10V and 0V.