First of all, let’s confirm there are text objects in your pdf file by going to View tab in Foxit PDF Editor or Foxit PDF Reader>Text Viewer, if it shows blank under text viewer mode, it means that it is an image-based or scanned pdf file which do not have text objects can be read out. Before you want to read out the PDF file again, please choose to use the OCR feature (Optical Character Recognition)in Foxit PDF Editor to make image-based texts into searchable or editable texts firstly.
If the text objects exist in your pdf file, you can go to File>Preferences>Speech, check if the voice in the same language as your file is chosen. Please note, if you don’t see the preferred language in the drop-down lists, you will need to download that language pack from Microsoft. Click here to know how to download and install a new Text-to-Speech language for Windows 10. And restarting computer is needed after install. Finally, you can select View > Read > Activate Read to activate Read Out Loud and read pages.