What kind of data is in the Excel file? Without knowing that, it's impossible to say if it can be converted.
The simple answer is that there are conversion programs and web sites out there that can convert between a large variety of formats. It all depends on what data you want to convert.
Yes, I know that Excel makes .xls files. We need to know what kind of data is actually in the file. Is it addresses? Is it waypoints with latitude and longitude coordinates? Is it Points of Interest?