What is a lizard viviparous or oviparous?

Answer 1

Oviparous means that the animal lays eggs that develop and hatch outside the mother's body. In reptiles, turtles are an example of oviparous animal.

Ovoviviparous means that an animal lays egg but the egg stays in mother's body. The embryo receives nutrients from yolk sac instead of the mother itself. In reptiles, Grass snake is ovoviviparous

Viviparous means animals retain the egg inside the mother uterus, but the embryo receives nutrients from the placenta. It's mostly restricted to mammals.

But many skinks and possibly also other lizards do have placenta like structures capable of transferring nutrients.
Brian K. Speake, Jacquie F. Herbert and Michael B. Thompson
Evidence for placental transfer of lipids during gestation in the viviparous lizard, Pseudemoia entrecasteauxii

Answer 2

If a lizard is viviparous, it gives birth to live young. If it is oviparous, it lays eggs.

Answer 3

Mostly they are Oviparous, although many species are also viviparous ( like most New Zealand Geckos). It very much varies between species