The file appears to be a large-scale Microsoft Excel dataset, likely part of a series (indicated by "File2") containing approximately 1 million rows of data (denoted by "1M").

While the specific proprietary contents depend on the source it was downloaded from, files with this naming convention are frequently used for:

Testing the speed and stability of data analysis tools like Power BI, Tableau, or Python's Pandas library.

This format was introduced in Excel 2007 and is compatible with most modern spreadsheet software, including QuickBooks Online and Adobe Acrobat . Managing Large Files (1M+ Rows)

A single worksheet in an .xlsx file can hold up to 1,048,576 rows and 16,384 columns . Since this file is labeled "1M," it likely pushes the software to its near-maximum row capacity.

Opening a 1-million-row file can often cause standard laptops to hang or crash. To handle this effectively, you can: How to open, read and edit an .XLSX file - Adobe