IDE stands for Integrated Development Environment. This are software programs or platforms used to program. They usually contain a code editor, a compiler (or interpreter) and a debugger. Since all of it is in the same interface, it becomes quite easy to use.
Unlike in our TC1017 class, in which we had an editor (Atom) and a terminal to compile (Bash in my case), IDEs have everything in one place, which means that just with the click of a button, you can compile and run your program, and with another, you can debug it without spending 5 hours of your life finding a semicolon.
In my case, I used NetBeans for programming in Java. I would recommend it, since it works, but the User Interface (UI) is not too friendly. I tried using it for TC1017, but after figuring out how to use C++, we were told that on the exam we were going to use a terminal to compile our programms, so I obviously did not use it.
Another good IDE that many people seem to recommend is Eclipse. I do not know much about it, but will leave the webpages below.
In conclusion, and IDE is basically a combination of tools that you would otherwise need to run manually. So, they are really helpful.