Computer programming is confusing to most people, code can even be confusing to computer programmers and this is why some principles were institutionalized to ensure that code is easier to maintain and extend, this way several people can collaborate on projects and pass it on. Without these principles concepts like "open source" would have been near impossible to pull off.
These principles are known as the SOLID principles, an acronym. Let's talk about the first one that forms the foundation for the rest. The S stands for "single responsibility". What this means is that a block of code/class/module should do only one thing. For example, a block of code written to calculate interest accrued on a loan will handle just that task, it won't be the same block of code to handle amortization on a loan.
This separation of responsibility helps with ensuring cleaner code that's easy to maintain and extend. Now imagine we suddenly to change our interest rate, we know where to look because our different blocks of code handle single tasks. By breaking down huge projects into simple blocks of code it's easier to compartmentalize and fix issues wherever they arise.
If you want to surprise a software engineer ask if their code implements SOLID principles. As a software engineer, frontend or backend you have to be aware of SOLID principles. The implementation of SOLID doesn't exactly improve the performance of your code. It does however ensure that your code outlives you.