It means that you get broadband for your computer, but no old-fashioned phone connection. There will be a physical cable (made out of glass fibre) between your house and the nearest street cabinet, but it won't be electronically programmed to allow you to have phone calls.
I'm no expert,; if I'm wrong in any way I'm sure someone more knowledgable will come along and put me right.
You DO have a physical phone line coming into your home but it ONLY serves a broadband router. You CAN'T plug a landline phone into it, as the relevant TalkTalk package doesn't include landline calls.
Such a deal is particularly useful for people who've got mobile phone plans that give them 'unlimited minutes', meaning that they never use their landline phones to make calls anyway.
I recently wanted to get a phoneline with no broadband for my 90 year old mother.
Impossible!
You can get broadband only, but not landline only.
Stop the world, I want to get off.
Helping TCL to help Hopkirk:
https://www.bt.com/landline/deals
(See the 'Don't have broadband?' link for a phone number to get a possible discount).
However, even with a discount, those prices look far higher than simply using a basic mobile phone (such as one of the Doro range, perhaps?) together with an 'unlimited calls' package. (e.g. a fiver a month from Asda Mobile).