The issue here is that you may start the year with 50 employees, and end it with 60, so without understanding the real story behind, you may assume that your headcount increased by 10 employees. While the truth is that you had some hires, some exists and some transfers in and out of this department.
The best way to visualize this story is through a "waterfall chart"
Step 1: Input your data to include the starting headcount and employees changes including hires, exists and transfers. The last field which is the ending headcount should be the sum of all the above.
Note: added headcounts should be positive numbers, while exists or outside transfers should be negative numbers.
Step 2: Select your data and go to Insert -> Insert Waterfall or Stock Chart -> Waterfall
Step 3: Once you see your waterfall chart, go to the last bar indicating the ending headcount, click on it once to choose all the bars, then click another time to choose this specific bar, then right click on it and choose Set as Total.
Now try to use this technique to understand and communicate other stories such as inventory change or cashflow management.