Part of the heraldic badge of the Prince of Wales, the German phrase 'Ich dien' has what meaning?

The Prince of Wales's feathers is the dexter heraldic badge of the Prince of Wales. It consists of three white ostrich feathers encircled by a gold coronet. A ribbon below the coronet bears the German motto 'Ich dien' (German: (ɪç ˈdiːn), "I serve"). As well as being used in royal heraldry, the badge is sometimes used to symbolise Wales, particularly in Welsh rugby union and Welsh regiments of the British Army.

The first Prince of Wales to use the badge in its modern form (i.e. three white feathers encircled by a coronet, and with the motto 'Ich dien') was Prince Arthur (1486–1502), eldest son of Henry VII, at the beginning of the 16th century. It was also widely used by Prince Edward, son of Henry VIII and afterwards Edward VI, although he was never formally invested as Prince of Wales. Feathers continued to be used as lesser royal badges, by Elizabeth I among others, until the end of the century.