Depending on what you want to do, you can export the correspnding product information again, edit the data in Excel and reimport it.

Thank you for your response. 

However, once l've downloaded the module. How do l go about uploading it into Odoo. I've searched the internet for help but nothing for Version 12.

Hi,

There is a module available in the Odoo store for such a process named 'Mass Editing', but the same is not seems to be available for the v12. But what you can do is that, as the v11 is available you can try to install the same in v12 and see whether it works, most probably without ay change or with a few changes it will work in v12.

1. https://www.odoo.com/apps/modules/11.0/mass_editing_v11/

2. https://github.com/ronozoro/mass_editing

Thanks