Telescope lens is a phrase almost nobody in the hobby uses, which is why searching for it turns up such a mixture. It usually means one of four things, and knowing which you mean makes the answer straightforward.
The objective, if the telescope is a refractor
The lens at the front that gathers the light. Its diameter is the aperture and its quality is most of the price of a refractor. Reflectors have no such lens at all, which is why the word does not travel well across the shelf.
The eyepiece, which is what most people mean
The small removable optic you look into. It sets the magnification and can be swapped, which is why one telescope can give many different views. If a listing offers extra telescope lenses, these are what it means.
The barlow, the reducer and the corrector
Optics that go between the two: a barlow multiplies the focal length, a focal reducer shortens it, and a coma corrector or field flattener cleans up the edges of the field for a camera. All three are lenses in a telescope and none of them is the telescope's lens.
What people are usually shopping for
Almost always eyepieces. The useful advice is to buy fewer and better: one good low power eyepiece changes more about a telescope than a set of six cheap ones, and eyepieces move between instruments so they outlast the telescope they were bought for.
Questions people ask about telescope
What is a telescope lens?
Ambiguous: it can mean the objective of a refractor, the eyepiece, or an accessory optic like a barlow. Most searches mean the eyepiece.
How much do telescope lenses cost?
Eyepieces range from a few pounds for a basic plossl to more than a small telescope for a premium wide field design. One good one beats several cheap ones.
Do reflector telescopes have lenses?
Only in the eyepiece and any accessories. The main optic is a mirror, which is why reflectors show no colour fringing.