We can guess what is in the oven only by the smell we smell in the kitchen air. That is the sense of smell.
Particles from food, liquids, flowers, etc. reach our nose and dissolve in the tissue lining the inner roof of the nasal cavity, the olfactory mucosa. There the information is transformed, to be conducted, through the olfactory nerve, to the brain, where it will be decoded.
The ability of our sense of smell is significant. We can distinguish thousands of different odors and identify strong smelling substances even when very diluted. Regarding the sense of smell of other animals, ours cannot be considered one of the most developed. The dog, for example, has a much finer sense of smell.