Your mesh does not look bad, although it seems that you need more elements both in the flow and normal directions.
The y+ value is the value of the dimensionless normal distance of the first element near the wall. This is a post-processing value given by Ansys Fluent, but there are calculators online that give a good estimate. The value is important for mainly two reasons:
y+=1 is the separation between the viscous sublayer and the rest of the boundary layer. For maximum accuracy, the y+ of the first cell should be less than one ( y+ around 5-20 is reasonable).
y+ around 250 is a good approximation of the width of the boundary layer.
In summary: setting values of y+ gives you the location of the first cell and the extension of the boundary layer. A good number of cell layers in the normal direction is around 15-50.
If I were you, I would read about the basics of turbulent boundary layers so that you understand the previous information, and I would review tutorials that are available on the internet.