Our goal is to gather data from an analog range sensor. This device must be connected to one of the analog input pins. We also need to connect it to power and ground pins. According to the documentation for the GP2Y0A21YK, the sensor has three connections: Vo, GND, and Vcc. With the sensor pointing up, the left-most pin is generally Vo, the output that will connect to Arduino A0 to provide analog input. The center pin is ground, which connects to one of the Arduino GND connections. The right-most pin will be Vcc, the supply voltage that will connect to the +5 V pin on the Arduino.
Many of these devices have a little JST three-wire socket. We can buy a nice little JST three-wire jumper. The color coding of the wires on the jumper may not fit our expectations very well. We may wind up with Vcc on the black-colored wire (black is often used for ground) and the ground connection on the red-colored wire (red is often used for +5V.)