One approach is to say that reality causes us to have perceptions of how reality is like. So, the apple causes us to have a perception of the apple. We see the appearance of the apple- its red skin, its round shape. The appearance of an apple is what allows us to infer the apple. Knowledge of reality is then a matter of inferring from appearances about how things are like.
The duck-rabbit illusion, the old-young woman illusion show that perception is not just passive but that there is interpretation of the images. We can interpret that duck-rabbit image to be either a duck or a rabbit, and the old-young woman image to be either an old woman or a young woman. This is to say that what is really there is also a matter of how we judge or perceive what we sense or see. So, the relationship between consciousness and reality goes in two directions.
An alternative is to see knowledge of reality as a coherent web of beliefs. We have a scientific theory of atoms that functions as an explanation of what solid objects, such as the table, are made out of.
