The raw data are the magnetometer readings along the X, Y and Z axes. The data sheet for the device will explain what the numbers actually mean, so you should go through it very carefully.
Magnetometers need to be corrected for offset and scale errors along each axis, so you will need to understand how that is done in the program and modify the procedure to correct for the errors in your particular device.
The angle is the heading with respect to magnetic North. The heading will be incorrect if magnets or iron-containing materials are anywhere nearby.