When 3D printing, it is crucial to have a level print bed to ensure proper adhesion of the printed object. If the bed is not level, the print may fail to adhere properly and can potentially peel up during the printing process.

To check if the bed is level using this grid, you would 3D print the grid and observe how it adheres to the bed. If the squares are printed consistently without any lifting or peeling, it indicates that the bed is likely level. However, if you notice any lifting or peeling of the squares during the print, it suggests that the bed may need to be leveled or adjusted to achieve better adhesion.

By using this grid as a test print, you can assess the levelness of the bed and make necessary adjustments to ensure successful 3D prints without any adhesion issues.

Read more here:

https://help.prusa3d.com/article/bed-level-correction_2267