Female DC Connector 5.5x2.5
These are connectors with a female power pin , a terminal block and cables that are connected in to the terminal block that is on the board.
This terminal block is a screw type terminal block where cables are connected in to it and then screwed to fix them tightly on to this terminal block hence reducing loose connections, the female pin on the male connector is compatible with the male power pin.
This terminal block has markings on it that show positive and negative, The – or minus sign shows where the negative terminal is to be connected and the  + or plus sign shows where the positive terminal is to be connected.