It is the password on your device to access the network. If you are trying to use the phone as a hotspot, if it is at all possible, it would be done this way...
- Go into "Settings" and in the "Wireless & networks" section tap "More".
- Now tap "Tethering & portable hotspot".
- For "Wireless Tethering" tap "Set up WiFi hotspot"
- On this new screen, you will see options for a "Network Name", "Security", "Password" and "Network Band". You can change them or keep them as is. It is really up to you.
- Now you would just need to search for the hotspot by name using the second device.
NOTE: While a WiFi hotspot feature is built into Android, some service providers/carriers, especially in the United States, hide it. You would then need to see if you can locate an app that you can install to help with this.