Your company might be requiring that you have to submit your receipts of house rent and other tax free heads like medical along with the tax declarations you had made in the beginning of the year.

Steps to be followed -
1. Enter the details in Comments / Actual columns
2. If you have declared house rent or if you have taxfree components which you have received in your monthly salary then you will need to update the supporting for them
3. Click on "Upload" to upload bills and receipt against submission. Individual files of upto 4 MB are allowed
4. Click on "Submit" to submit these details to payroll manager for verification and approval

Related article - Tax saving declaration.