index.js

"use strict";

const Company = {
    org: "Mobiquity",
    employees: [{
        title: "Vice President",
        employees: [
            {
                title: "Sales Lead",
                employees: [{title: "Salesman"}],
            },
            {
                title: "Marketing Lead",
                employees: [{title: "Marketingman"}],
            },
        ],
    }],
};

function countEmployees(prev, next) {
    // count *this* employee
    let sum = prev + 1;
    if (next.employees && next.employees.length) {
      // count any nested employees
      sum += next.employees.reduce(countEmployees, 0);
    }
    return sum;
}

console.log(Company.employees.reduce(countEmployees, 0));