Yes, subject to certain limitations.
You can only import list data into 1 of 4 lists:
You can import either in Microsoft’s supported workbook format (.xls or .xlsx, depending on your version of Excel) or CSV format.
Intuit offers a free Import Excel and CSV Toolkit, which includes a PDF manual, CSV and .XLS example import files, and a reference guide explaining field names. It’s a compressed executable file, which extracts those files when run. Additional information is available in this Intuit knowledgebase article.
You can use another import file type, Intuit Interchange Format (IIF), to import unlinked transactions. See our article on the capabilities of IIF files for more information.