Cables:
1) Power cable from PC to electrical outlet (direct) or via UPS, surge protector, or extension strip that is connected to the wall outlet..
2) Video cable from PC's motherboard port or GPU port to monitor. PC must have the necessary video drivers installed. HDMI, Display port, DVI, VGA...
3) Ethernet network cable, Cat 5e or better, to connect PC to network - unless you are using wireless. I recommend using wired if at all possible. Or at least long enough to get the new PC up and running with applicable drivers and updates. Then when all is working shift to wireless if desired.
4) Cables for any devices that will be directly connected to the new PC. E.g., Keyboard, mouse, webcam, external HDD or SDD, an attached...