AWS, JavaScript, React - Deploy Web Apps on the Cloud - JavaScript Joining Arrays

The video tutorial explains how to work with two arrays named 'girls' and 'boys'. The 'girls' array contains four elements, while the 'boys' array contains five. A third variable is used to combine these arrays using the concat method. The combined array is then outputted using the getElementById method. Finally, the video demonstrates how to preview the output in a web browser.

What is the purpose of the getelementbyid method in this context?

What can be observed when previewing the file in a web browser?