Amortization is basically just a way of splitting the cost of something out over multiple years to change how much you may owe in taxes.

In this case, previously software engineers' salaries were considered an operating expense like any other salary, and the full amount of that was used to decrease how much profit you have to pay taxes on. Now you can only write off a portion of the salary, having to split it over multiple years' taxes instead.

This is really common with R&D expenses, physical equipment, etc. The big change was that software engineers are now considered an R&D expense rather than someone working to assemble a final product, for example.