If the Arduino board has a power supply correctly connected to either the USB Jack or the DC power jack, then the 5V pin provides access to the Arduino 5V system voltage. The LCD display might be powered with 5V by connecting to the Arduino 5V pin assuming that it does not require more current than is available. Without knowing the exact LCD display specifications for your device, I can’t say for certain.
If you provide more information about your hardware, intended wiring schematic, and Arduino power source, then this forum can provide you with better answers.