Short answers, pulled from the story.
A lenticular galaxy, designated S0, is a disc galaxy that has a large-scale disc and a prominent central bulge but no large-scale spiral arms. Unlike spiral galaxies, lenticulars have used up or lost most of their interstellar matter and have very little ongoing star formation; all their stars are thought to be older than about a billion years.
Lenticular galaxies without a central bar are sorted into classes S01, S02, and S03, where the subscripted number indicates increasing dust absorption in the disc. Barred lenticulars run from SB01 through SB03, reflecting the prominence of the central bar; SB03 galaxies such as NGC 1460 have the most well-defined bars.
Lenticular galaxies have exhausted or lost most of their interstellar gas, leaving little raw material for star formation. They show essentially no hydrogen alpha or 21-centimetre emission, which are the signatures of the cool gas needed to form new stars.
Three main theories compete. In the faded-spiral scenario, a spiral uses up its gas, star formation ceases, and the arms dissolve. In the merger scenario, two spirals collide and produce a disc-like, arm-less remnant with higher surface brightness and more globular clusters. A third theory proposes that disc growth occurred through accretion of gas and small galaxies around a pre-existing spheroidal structure.
Lenticular galaxies follow the same Tully-Fisher relation as spiral galaxies, which links rotational velocity to luminosity, but are offset by approximately delta-I of 1.5 magnitudes. This offset indicates that their stellar populations are older and redder, consistent with the idea that lenticulars were once spiral galaxies that have since stopped forming stars.
LEDA 2108986 is an extremely isolated, low-luminosity lenticular galaxy. Its isolation makes it difficult to explain using the ram-pressure stripping or galaxy harassment scenarios, which require a dense cluster environment, and it has also been cited as a test case for the disc-growth-by-accretion theory in isolated settings.