How do languages work together?

Question

How do programming languages work with each other? I've read articles saying u need multiple languages for a single project , and I understand that cause languages have their strengths and weaknesses, but how? I'm a beginner learning c++ and would really appreciate if someone could give me some exposure as to how it all works. For example if I were to program sth in c++. What do I use for the gui? QT? Could I use another programming language for the GUI? If so how do I "MERGE" that with my c++ code?Thanks!

Answer 1

actually you'll just need 1 in a project... If you're not using HTML.
Maybe learning more languages can be useful, because you'll make the project easier depending on what you want to make.

Answer 2

I also heard that kind of things. Like to see how they are actually used

Answer 3

Theres a Software that you can Make HTML and CSS within it.

Answer 4

i can explain you by giving an example
as we use android
basic language for android is java
but u can also use c++ or kotlin for building apps