One Death grabs the maiden's breasts and thighs, while the other comes crawling with an hourglass on his back. One interpretation is that she is a prostitute and that the hourglass on the posterior alludes to her hourly wages.
Presumably Holbein has looked at two different works by Niklaus Manuel Deutsch. On Manuel's famous picture of Death and the maiden from 1517 (image to the left) Death caresses the maiden and sticks his hand up between her legs. This eroticism is in contrast with the duke, where death comes in female form, and where there is no hint of eroticism.
Holbein probably copied the picture of Death crawling with a hourglass on the back from Manuel's other and even more famous work, i.e. the dance of death in Bern (picture below to the right).
The accompanying text goes: »Das lachen würt vermischt mit schmerzen / vnd die letsten der freüd bekümmeret das weynen / Sy furen ir tag in den guten vnd schnell stygen sy zu der hell«.
The first part is from Proverbs 14,13, which in Luther's version sounds: »Auch beim Lachen kann das Herz trauern, und nach der Freude kommt Leid«. In English: »Even in laughter the heart is sorrowful; and the end of that mirth is heaviness«.
The second part is from Job 21,13, which Elberfelder renders thus: »Im Glück geniessen sie ihre Tage, und in Ruhe sinken sie in den Scheol hinab«. In English: »They spend their days in wealth, and in a moment go down to the grave« (grave and Hell are two ways to translate the Hebrew "Sheol".
One may argue whether the young woman, like the rider, lacks a counterpart in Holbein's great dance of death, or whether she is parallelled by the countess. Both women are accompanied by the same Bible quote, Job 21:13.
Death is wearing the same hat before the king (letter D), the nobleman (letter K) and on the Holbein dagger. The same hat appears in the middle of the crowd in All men's bones.