@ramky159 As mentioned by @sdecandelario PHPExcel looks promising. They have a detailed documentation which I'm sure is more than enough to help you out!
I don't get it. PHPExcel will just get the data from excel. It is your job to store it in array and then insert it into DB. I don't know much about Slim, but I guess you can pretty much use basic SQL insert in any PHP framework. Just a simple google give me this link : scottnelle.com/616/connecting-slim-framework-mysql