How Do We Code?
Coding (or programming, as I like to call it) is changing. What used to be done directly on a computer, with specific hardware, is becoming easier and more ubiquitous. These days you can develop your program completely in the cloud and even deploy to a production server without having the files directly on your own computer. We've almost gone back to having dumb terminals.
Typically, you would set up a development environment on your computer(s) to produce your code in the language(s) of your choosing. This might include an Integrated Development Environment, or IDE. One of the most widely known IDE's is Eclipse. Another is MS Visual Studio (one of my favourites). The IDE has a workspace for editing code files, highlighting syntax, compiling and debugging code, and even deployment or connecting to a version control system.
Cloud Environments
Eclipse IDE
Visual Studio
Visual Studio Code
These days your dev environment, including very capable IDE's, are available online. Amazon is putting a lot of money into their AWS system, for example.
We will be using a teaching/learning IDE from Repl.it. Below are some examples of other web-based development environments:
The Eclipse IDE was designed to give developers full control of their environment. From colour and syntax-highlighting schemes to language plugins to linting, autocomplete, and debugging, Eclipse is a workhorse. For that reason, it is also extremely complicated and a bit bloated. It also has a steep learning curve.
Don't let that sound like a bunch of negatives towards Eclipse. It is extremely powerful and used across the globe for code development.

The Eclipse IDE allows you to program in several languages using plug-ins
Microsoft gets a bad wrap for no good reason. People who dislike Microsoft products do not know what they're missing when it comes to development environments and MS Visual Studio. Even back in 1999-2000 with version 5, the environment was solid, mature, and full of incredible features designed to make programming faster and more professional.
I am a tad biased, since I've been using various versions of MS Visual Studio since I was about 17 years old, but it is seriously worth a look - even (or especially) the express versions.

Visual Studio has been around since the 90's and is a very mature product
By far, one of the best code editors out there is Visual Studio Code. It is not a complete dev environment, but plug-ins can get it pretty close. From their own site:
Visual Studio Code combines the simplicity of a source code editor with powerful developer tooling, like IntelliSense code completion and debugging.First and foremost, it is an editor that gets out of your way. The delightfully frictionless edit-build-debug cycle means less time fiddling with your environment, and more time executing on your ideas.

The procedure known as compiling is the act of running a program (the compiler) to read through your code and convert it to something a computer can understand. It might get compiled down to assembly or some other machine-level language that is meant for the processor to understand, not our human eyes - essentially to binary instructions.
Interpreting
Interpreted code, like JavaScript and Python, has a "middle-man" translating the code to machine language instruction-by-instruction. Instead of compiling all the code into machine language, it does this as necessary. This can be costly in terms of performance but also has many benefits like fixing code on-the-fly and using the same code for any kind of hardware.
There are many great videos on YouTube explaining the differences between compiled and interpreted code - I suggest you watch a couple and find the one which helps you the most.