"From Mozilla to Excel" doesn't make sense.
Mozilla isn't a file format. It's a browser.
I assume that you mean from HTML to Excel.
There is nothing inherit in JSP for working with or creating MS Office files but there are 3rd party libraries for doing so from
Java. Excel is also capable of working formatted text files (CSV, HTML tables, etc).
See:
http://faq.javaranch.com/java/JspAndExcel