Vitamin A is one of the few nutrients where you can get too little or too much, so both directions matter. Its best-known job is vision, particularly your eyes' ability to adjust to low light, and it also supports your immune system and skin. When intake stays low over time, that's associated with poorer night vision and a weaker defence against infections.
Shortfalls aren't rare: US national survey data (NHANES) suggests around 45% of people don't get enough to meet the recommended intake. Adults need around 900 mcg a day for men and 700 mcg for women, from liver, eggs, and dairy, plus orange and dark-green vegetables like carrots, sweet potatoes, and spinach.
The other direction is the ceiling. Because vitamin A is stored in the body rather than flushed out, it's best not to exceed 3,000 mcg a day. That limit applies to the preformed vitamin A in animal foods and supplements, not to the beta-carotene your body makes vitamin A from in plants, which doesn't carry the same risk.