The camera lens plays an important role in the actualization of high resolution photos. While a low resolution lens will not make the difference between high details differences in an image, a high quality image can easily pick up the details before translating them to the sensor.
Understanding lens resolution is a science in itself. I took me quite some time to make head off the tails of an elaborate Cambridge document I chanced upon (I read guys, I read!), but I finally understood the role a lens plays in the quality of an image.
Diffraction is the bending of light as it passes from one medium unto another (hold onto that thought).
The clarity of the generated image depends on how accurate the translation of the rays onto the sensor is. The more the diffraction the more blurred the image edges will be. This means that no matter how good the sensor might be, the quality of the generated image will still be fuzzy. The quality of the lens with emphasis on its diffraction limit can be used to project a measurement value (MTF: Modulation Transfer Function) that will determine how well the lens handles every fine detail of the image.
An MTF value of one signifies perfect translation with the quality deteriorating as the value tends towards zero
Cambridge has perfect notes explaining this concept in detail. All we need to know for now is that the lens quality determines how accurate the light rays translated onto the sensor will be.