How to get a randomly generated string in browser by using selenium, while it can't be found in the website code?

I need to get this randomly generated string so I can finish my task, it changes every couple seconds. However, I can't find any explicit name of the string that can be retrieved from the website's code. We just learned about using selenium to grab data, so I suppose it can be down with only selenium's function?Here 's the snapshot of the question and the code