Functions are one of the basics parts of Javascript. They are really powerful but it depends on ourselves when we declare them how powerful they can be.
Getting into a new programming language, most of the time, starts in the same way, declaring a variable and setting a value in that variable and it's really important to know how they work together.
If we want to understand how javascript works beyond your code, you need to know three different concepts or ideas that you will see repeated throughout the rest of your life as a programmer.