Yule is a complex term (cf. Yul, Jol, Yol, Yalda)
Yule was the old name for Christmas. In French it is called Noel, which is the Hebrew or Chaldee word Nule (Chambers’s, art. “Yule,” and Celtic Druids, p. 163).
In modern times it is often a  term for Christmas.
It is linked with an event:
 Winter Solstice
20-23 December
Alban Arthan,
Winter Rite
Winter festival
Yule - Litha
Midwinter - Midsummer
Winter Solstcie - Summer Solstice
In the Celtic Wheel of the Year it is linked with Yule, one of the 8 divisions of the year. 
In the Rume Circle,  Yule - Imbolc relate to Zima, i.e. the whole of the Winter period (see image)..