JavaScript Mastery from Zero to Hero - Prepare for Coding Interviews - Solution I - Sort Out Facebook Groups by Location

The video tutorial explains how to handle Facebook group data by defining a function called 'meetup by location'. It covers flattening arrays, using function arguments, and implementing the reduce method to process data. The tutorial concludes with filtering data by location and testing the solution.

What challenges are mentioned regarding accessing the string argument without affecting it?

Describe the role of the 'reduce' method in the context of this function.

Summarize the final outcome of the function when tested with different locations.