What is Meriva Phytosome Curcumin?
Well, http://meriva.org states that

Meriva® is a patented formulation of curcumin, a dietary phenolic, with soy lecithin (non-GMO)(1). The two compounds form a non-covalent adduct in a 1:2 weight ratio, and two parts of microcrystalline cellulose are then added to improve formulation, with an overall contents of curcumin of 20%

A phytosome is

[...]  a complex of a natural active ingredient and a phospholipid.
It is claimed that phytosome increases absorption of &quot;conventional herbal extracts&quot; or isolated active principles both topically as well as orally.
The complexation with phospholipid has been applied to many popular herbal extract or active molecules including [...] curcumin isolated from turmeric [...].

And Curcumin is

[...] is a diarylheptanoid. It is the principal curcuminoid of turmeric, which is a member of the ginger family (Zingiberaceae). Turmeric's other two curcuminoids are desmethoxycurcumin and bis-desmethoxycurcumin. The curcuminoids are natural phenols that are responsible for the yellow color of turmeric. Curcumin can exist in several tautomeric forms, including a 1,3-diketo form and two equivalent enol forms. The enol form is more energetically stable in the solid phase and in solution.

So, Meriva Phytosome Curcumin is a phytosome of curcumin developed by Meriva.