Android Read/Write BLE devices with RS232 serial port communication

Question

I am developing Android project to communicate with BLE (Bluetooth Low Energy) devices, the device i have following the communication interface is base on RS232 serial port communication.

I am following this https://developer.android.com/guide/topics/connectivity/bluetooth/ble-overview

My device have

Service UUID: 0x1523-1212-efde-1523-785feabcd123

Characteristic: 0x1524-1212-efde-1523-785feabcd123 (write/notify)

but no success in reading

Android document i am following is working with Characteristic UUID=00002A1C-0000-1000-8000-00805f9b34fb

but the required device is not.

Note: want to read data through Android mobile Bluetooth not by OTG or usb cable

what the difference between the 2 UUID's ?

Thank for your help in advance