Given an integer array nums, find the subarray with the largest sum, and return its sum.

This problem can be solved using Kadane's algorithm. Here are the steps:

1. Initialize two variables, max_current and max_global. Set both of them to the first element of the array.

2. Loop through the array starting from the second element. For each element, calculate max_current as the maximum of the current element and the sum of max_current and the current element.

3. If max_current is greater than max_global, update max_global with the value of max_current.

4. Continue this process until you've gone through the entire array. The value of max_global will be the maximum subarray sum.

Here is a Python code snippet that implements this algorithm:

def maxSubArray(nums):
    max_current = max_global = nums[0]
    
    for i in range(1, len(nums)):
        max_current = max(nums[i], max_current + nums[i])
        if max_current > max_global:
            max_global = max_current
            
    return max_global

This function takes an array of integers as input and returns the sum of the subarray with the largest sum.