People use photo editing software for a number of reasons. Some people use it in their personal life for tweaking pictures etc and others use it as part of their job role. There are a number of different photo editing software applications that are available, some are free and others are charged for.
Photoshop is probably the most well-known and is very popular amongst designers, but it is not cheap. Adobe has now swapped to cloud, allowing you to pay for it monthly on a leasing basis.
If you are looking for a free photo editor that has similar functionality to Photoshop then there is even a web based application that can be used by anyone. There is the option to upgrade to a premium version, but for many people the free version is good enough.
Always make sure that you try any software before you buy it and especially before you agree to any long term subscription.
It may take you some time to get your head round a new photo editing software package but often it is just practise. YouTube is a great way to find tutorials of how to complete different tasks that you may need to do such as layers and adding effects.