Avocados are energy dense fruits and an excellent source of good fats (mono- and polyunsaturated) (1, 2). Avocados are also a good source of potassium and fiber, which, as highlighted by dietician Bonnie Taub-Dix, are two of the nutrients that Americans don't get enough of, according to the 2015-2020 dietary guidelines (2). In addition, avocados contain carotenoids (vitamin A), vitamin E, and vitamin C (2, 3). Due to the fat content in avocados, they are also excellent in boosting the absorption of fat-soluble vitamins such as A, D, E and K (2, 3).
According to a research study, avocado consumption is associated with improved overall diet quality and nutrient intake, and reduced risk of metabolic syndrome (4). By shifting fat intake from a greater proportion of saturated fats (common in the standard American diet) to a greater proportion of unsaturated fats, one can build a healthier blood-lipid profile, which has many beneficial implications in cardiovascular health (3). Another study actually found that a moderate-fat diet incorporating avocado consumption decreased LDL cholesterol (known as bad cholesterol) compared to a moderate-fat diet without avocado (5).
Sources:
https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/fats-and-cholesterol/types-of-fat/
https://californiaavocado.com/lifestyle/8-reasons-why-california-avocados-are-a-superfood/
https://nutritionj.biomedcentral.com/articles/10.1186/1475-2891-12-1
https://www.psu.edu/news/research/story/avocado-day-keeps-cardiologist-away/