trying to change directories

Yes, the comma in the folder name is the reason why you can't change to that directory in Linux. Commas are used as delimiters in file paths in Linux, so they tell the operating system that the path ends there.

To change to a directory with a comma in the name in Linux, you need to enclose the entire path in quotes. For example, to change to the BOOKS, directory, you would use the following command:
cd "/home/user/BOOKS,"

The quotes tell the operating system to treat the entire path as a single unit, and not to interpret the comma as a delimiter.

Here are some other ways to avoid problems with commas in file paths in Linux:

You can rename the folder so that it doesn't have a comma in the name.
You can use a different character as a delimiter, such as a hyphen or an underscore.
You can use a symbolic link to the folder. A symbolic link is a special file that points to another file or folder. When you use a symbolic link, you can use the name of the symbolic link instead of the actual path to the folder.