A lot of times people assume that software engineers are sorcerers owing to how they are able to speak some complex language that most people don't understand. Anyone who hasn't written code professionally doesn't know half of the tale. Imagine writing several documents (in separate files) and having to call some features of those separate documents into a particular document in order to use some of the words in that other document, it sounds confusing right? Well sometimes software engineers get overwhelmed by the size of the project too.
We however have a construct that makes things easier for us, it's called "intellisense", it's like assisted driving or prediction keyboard. Because we work on projects that involve many files (the content of which we don't remember verbatim) the intellisense feature on our code editor helps guide and link us to the necessary files. Make no mistake, intellisense isn't very useful if you don't know what to write, it just makes things easier for those who know what they're doing.