Today will be one second longer than yesterday. And a second longer than tomorrow.
Believe me, this sort of thing can be a real pain when it comes to doing observational astronomy. But at least it’s not as bad as adding 10 whole days, as Pope Gregory XIII did in 1582, when the existing Julian calendar was seriously out of sync with the the heavens. And pity the poor buggers born on 29 February, who only get to celebrate their birthdays once every four years! A humble leap second is but a blip by comparison.