From Wikipedia:

Brigid's cross, Brighid's cross, or Brigit's cross, or (in Gaelic) Crosóg Brighde, though not recorded before the seventeenth century, is an Irish symbol that possibly derives from the pagan sunwheel. It is usually made from rushes or, less often, straw. It contains a woven square in the centre and four radials tied at the ends.

Many rituals are associated with the making of the crosses.[1] These were formerly commonplace but are now rare. Occasionally Roman Catholic homes still feature Brigid's crosses, especially in rural areas. It was traditionally believed that a Brigid's Cross protects the house from fire and evil.[2]

Brigid's crosses are associated with Brigid of Kildare, who is venerated as one of the patron saints of Ireland. The crosses are traditionally made on 1 February, which in Gaelic is called Lá Fhéile Bhríde (Brigid's feast day), the day of her liturgical celebration.

Brigid is also the name of a Celtic fire-goddess associated with the feast of Imbolc.

Brigid's cross (sometimes stylized) was used to represent Telefís Éireann and RTÉ 1 (later RTÉ One); in 1961 to 1987 and 1993 to 2000 as it is an unofficial symbol of Ireland.