Unable to select

hi im new to rhino but is there a way to select only a this area in rhino when it is a singular polysurface with the grid being created from isocurve?

nope, in this case you would have to create a 7x7 polysurface for example by creating one smaller one and arraying them in both directions then join. you could also extract the isocurves split the surface with them, shrink and join the surfaces. after you have created 49 joined surfaces to one polysurface, you can select that area with ctrl shift.

but one should ask what your further intention is maybe there is a simpler way of approaching your needs?

To build on @encephalon response it appears that the object is a single surface with multiple spans, not a polysurface. A polysurface is multiple surfaces joined together.

ConvertToBezier will split into a set of individual single span surfaces. The resulting surfaces can be joined together into a polysurface.

Split with the Isocurve option can be used to split a surface along isocurves.

Hello - you may be expecting behavior similar to SubD surfaces from single Nurbs surfaces - you do not get that - but if you make a SubDPlane and Ctrl-Shift (=sub-object) select a face, you will see that it works in that case.