Listen first to the track mix with a particular focus on the wind section.
That feeling is what we attempt to evoke with the text. If you've ever had the opportunity or taken one to just stand and be silent as twilight turns to day, you'll understand the 'magic' referred to in this song. The song verses are very poetic in text, contrasted with a jazzy scat chorus as its hook. Older choirs can bring the nuance and dynamics it needs to really shine. Intermediate choirs should be able to perform it without struggling.
'Winter Magic' is a jazz waltz that may sound a little more difficult than it actually is to sing.