From the press office of the Queen of England:
The Queen has today been pleased to confer a Dukedom on Prince Henry of Wales. His titles will be Duke of Sussex, Earl of Dumbarton and Baron Kilkeel.From Wikipedia:
Prince Harry thus becomes His Royal Highness The Duke of Sussex, and Ms. Meghan Markle on marriage will become Her Royal Highness The Duchess of Sussex.
In the British peerage, a royal duke is a member of the British Royal Family, entitled to the titular dignity of Prince and the style of His Royal Highness who holds a dukedom. Dukedoms are the highest titles in the British roll of peerage and the holders of these particular dukedoms are Princes of the Blood Royal. The holders of the dukedoms are royal not the titles themselves. They are titles created for legitimate sons and male-line grandsons of the British monarch, usually upon reaching their majority or marriage. The titles can be inherited but cease to be called "royal" once they pass beyond the grandsons of a monarch. As with any peerage, once the title becomes extinct, it may subsequently be recreated by the reigning monarch at any time.-Robert Wenzel