As the name suggest, Software Engineering is the field which focuses on the development of the software and its maintenance. Software is a collection of instruction which are provided so that the computer can perform some definite program as required by the user. For example, Browser you are using is a software. If you become a software engineer, then you will have to develop new software or have to maintain the software from reported bug's.

For more information regarding Software Engineering, consider the link below:

https://www.careers360.com/courses/software-engineering-course

I hope this helps. Wish you a great eve!