it's a stylised version of a harp representing Ireland

the top right is Scotland, the top left and bottom right is England. When it's displayed in Scotland you get two Scotland single-lion and one England triple-lion

nb: in heraldry you're meant to refer to it as if it's a shield in front of you, so left in the image is "heraldic right" - this note for the pedants, but I'm just using left to mean left on the image as you look at it in this comment.