This is the set of observable characteristics of an organism, includes it’s physical properties, how it develops, it’s behaviors. Essentially, this is the set of markers that make Thing A different from Thing B.
This things may be caused on genetic makeup (the “genotype”), or they may be caused by the environment in which the organism has developed.
For a human, these characteristics might be height, eye color, limb length, natural body fat percentage, cardiac capacity, etc.