you need Microsoft Excel for that. Select the value in Excel, copy that, then in Solid Edge variable table Right click on Formula cell and select past link. In this case you can modify this variable in Solid Edge, if you change the value in Excel.
Note: you should not change the path of this Excel
Sending values from Excel to Solid Edge will need to run both programs on your computer. This is done by COM (also known also "object linking an embedding" , OLE) . Excel will send data to Solid Edge, which the will write the value to the variable.
So Solid Edge has opened the file in question.
File properties are stored in a well known format in a sub section of the .par file. This is defined by Microsoft and is equivilent to the information in excel or word files. As a consequence windows explorer can show information like title or author without Solid Edge installed on the computer.