What does the VLOOKUP function do?

The VLOOKUP function is specifically designed to search for a specified value within the first column of a table or range and then return a value from a specified column in the same row of that table. This is why the correct answer is that it looks for a value in a vertical column.

The functionality of VLOOKUP is particularly useful when working with datasets where you need to find information associated with a unique identifier found in that vertical column. For example, if you have a list of employee IDs in the first column and their corresponding names in the second, you can use VLOOKUP to find a name based on an employee ID.

The other options describe functions or concepts that do not align with what VLOOKUP is designed to do. Searching in a horizontal row, combining values, or counting entries do not capture the core purpose of the VLOOKUP function, which is focused on vertical search within a structured data set.