The link to your website

This link will be shown in the bottom left corner of the podcast page on iTunes, and in other podcast clients.

If you leave this value empty, dependening on your configuration the link on iTunes will point to your Podigee blog, or your own domain.
One common use case would be if you use the podcast for marketing purposes, you could link to you company's website to drive your listeners there.
It's important that the link contains the correct scheme, the two allowed are "http" and "https". E.g is  correct, while is NOT.