Relationship between mesh resolution and element size

I’m making a convergence with refinement mesh and I wish to know what is the relationship between mesh resolution and h-size. Is it resolution = 1/h or some other metric?

When you say h-size, do you mean: mesh.hmin()?
If so, check the C++ documentation
And you will find that:

Compute minimum cell size in mesh, measured greatest distance between any two vertices of a cell.

Yes, that’s exactly what I mean as h. Thanks