Hi,
You can follow steps mentioned below;
1.create list
2. use get files from folder action, o/p of this action is files
3. check if files.count>0
4. if step 3 is true then add files[0] to list var created in step 1 using add item to list action
5. use that list var directly as attachment when sending an email
You can use above set of action i.e. from step 2 to 4 in loop if filename to check is varying every time based on row in excel file.
please find below image for reference: note according to below code o/p filename with it's path will be in lstAttachment var, which can be used further.

Please mark this as solution if it helps you solve issue. Happy to help you more.