This verse, 1 Chronicles 27:26, is part of a list detailing the officials appointed by King David to oversee various aspects of his kingdom's resources and administration. Let's break down what it means:

"Over those who did the work of the field for tillage of the ground..." This indicates a specific group of people: agricultural laborers or farmers who were responsible for cultivating the land and preparing it for planting crops. "Tillage of the ground" refers to plowing, breaking up the soil, and otherwise working the land to make it suitable for agriculture.

"...was Ezri the son of Chelub;" This tells us that a man named Ezri, whose father was Chelub, was appointed as the supervisor or manager of these agricultural workers.

In essence, the verse signifies that Ezri was in charge of overseeing the agricultural workforce responsible for cultivating the land in King David's kingdom.

Significance:

Organization: This verse, along with the surrounding verses, highlights the organized and efficient administration that David established in his kingdom. He understood the importance of managing resources, including agriculture.
Importance of Agriculture: Agriculture was vital for sustaining the population and economy of the kingdom. The appointment of an official like Ezri demonstrates the recognition of this importance.
Administrative Structure: It provides insight into the hierarchy and specific responsibilities within David's administration. Ezri wasn't just a farmer; he was an administrator, responsible for managing a workforce and ensuring agricultural productivity.

In short, it's a small detail in a larger picture showing how King David structured his government to manage the kingdom's resources effectively.