Here is a basic example of sending and receiving data with a Bluetooth Low Energy device that implements the Nordic UART Service. Using Python and the bleak BLE library. The included Arduino code is meant for an Adafruit Feather nRxx2 Bluefruit LE and will simply echo back any BLE UART data that it receives. The Python code will connect to the device and send a fixed message at a regular interval and print any lines of text it receives back.
A few options can be provided to the Python program, like --scan which will
scan for BLE devices and list their addresses and names for you.
python python_ble_uart_example/__init__.py --scan
The script can be provided the name your device advertises and it will connect and run the echo demo:
python python_ble_uart_example/__init__.py --name "BLE Echo Thing"
Or you can provide the address, which is a bit faster because no scan is required:
python python_ble_uart_example/__init__.py --address "xx:xx:xx:xx:xx:xx"