File Upload element gives you the ability to attach file into a form. The snapshot of the form shown below is taken from the CRM application found in default Joget's installation package.
Figure 1: File Upload
Figure 2: File Upload Properties
ID: Element ID
Label: Element Label
Size: Width of the element
Read Only: Determines if one can upload file.
Download as Attachment: Determines the download behavior.
Figure 3: File Upload Properties - Validator
In the validation tab, one can further fine tune on the kind of file that can be accepted.