An ish eshkolot in modern Hebrew is a Renaissance man. You can often hear it used today in the context of lamenting the lack of them, the dearth of great scholars at home in the worlds of Torah, science and general culture and who are able to combine the best of each sphere.
The phrase comes from eshkol, which is a bunch, as in a bunch of grapes. The prophet Micah bemoans the state of the Jewish people when he says, There is not a bunch (eshkol) to eat (Micah 7:1).
Rashi and other commentators explain that Micah was not expressing disappointment with the selection at the greengrocers, but rather, eshkol is a metaphor for a righteous person who can teach others. As the next verse declaims, The pious are vanished from the land.
In the Talmud, an eshkol referred to a scholar who had achieved universal knowledge. Rabbi Akiva was famously called an eshkol. The midrashic text, Shir Hashirim Rabbah, makes a play on the word by splitting it into two: ish (meaning man) and kol (meaning all). An eshkol is a man who knows it all, an ish kol.
Some link eshkol to the ancient word for school or scholarship: eskola.