None of them really do anything.
Their government is not structured like ours. The Royal Family performs a lot of diplomatic functions that would be undertaken by members of the State Department, the Department of Defense, or the Vice President in the U.S. They are supposed to remain above or outside of politics, and for the most part, the Queen has done a pretty good job of that. At 94, she is still working. Her husband and daughter have been both tremendously productive in their roles as miltary figureheads and as patrons of hundreds of charities.
One of the benefits of their system is that it doesn't change players every four or eight years, which adds stability. Younger people think that's stultifying, and Americans think it limits opportunity; but look at the chaos now going on as Biden rips up many of Trump's accomplishments, after Trump ripped up Obama's usurpations, and Wall Street/Big Tech throttle our basic rights.