[Tayyub]

What does Element Quality mean in meshing and how does it effect our results?

[fluid23]

That is probably somewhat subject to what software and mesh type you use. In star-ccm+ it's called cell quality which is essentially a measure of non-orthogonality of your cells. For polyhedral cells you typically want the flow approaching at least one face more or less head on so having a cell quality very close to 1 means that all faces roughly point away from the cell center and at least one face should meet any incoming flow at a 'good angle'.

At least that is my understanding, perhaps someone else can give a better explanation.

[kulls]

Grid quality is the overall measure of quality parameters to be considered for differentiating a good grid from a poor grid.

A good quality grid easily runs in the solver and solutions converges faster.

You can individually check for cell's angle, determinant, warpage. Or just simply check a single parameter called grid quality to ensure your grid is useful for a simulation.