The documentation answer:
You can use SAS/ACCESS Interface to PC Files to read data from PC files for use in SAS reports or applications. You can use SAS data sets to create PC files in various formats. SAS/ACCESS Interface to PC Files includes accessing data in Microsoft Access database files and Microsoft Excel workbook files as well as in other PC file formats.
Basically, you need it to work with Excel files especially things like Access files or if you're using Excel as a 32 bit version and SAS 64 bit version.
https://documentation.sas.com/doc/en/pgmsascdc/9.4_3.5/acpcref/n1wqgr4en68w78n1lzzhwqdb6m3y.htm#:~:t....
Are you looking for information beyond this?