Programming question

I understand that you are not familiar with the development. It's best to use technologies for websites and applications that are easily scalable and maintainable. React is often used for the interface, Node.js or Ruby on Rails are good for the server side. But you should understand that the cost of creating an online marketplace mobile app is formed in relation to completely different factors. That is, the price depends on the size of your project, the functionality to be implemented there, and the developers' working hours. All of these things influence the price of development, but certainly not the programming language.

I don't even know what programming languages applications are built in. I remember that at university I had to pass a course on C++, but I didn't do the assignments myself, my boyfriend did it for me.