In python just have to do this:
1 - Import library:
2 - Open port:
ser = serial.Serial('/dev/ttyUSB0', 38400, timeout=1)
Setting the correct port and baudrate.
3 - Read data:
read = ser.read(X)
Where X is the number of bytes you want to read together. If you just write read = ser.read(), you read 1 byte.
I recommend you to read just one byte at a time because if you read more than one, it will kept as string and you cannot modify it. For avoiding it and be able to modify you have to save it as list but I haven't the code here right now.
And, the rest is treat that data in functions or whatever you want.