A lead generation sales funnel is just a mini website, essentially. The most basic of these consist of a lead capture page and a tour page. A lead generation sales funnel is designed to capture visitors' contact information by leveraging valuable information for a visitor's contact information. Once a visitor enters their contact information, they are then sent to a tour, or informational, page that contains the information they are looking for. This page is designed to contain information and funnel them towards a particular call to action, which is inquiring for more information or buying the product/service.
The process of bringing in visitors with enticing offers or information and then funneling them into becoming a customer is what a lead generation sales funnel is designed to do.