Monounsaturated fat is one to actively favour rather than limit. Unlike saturated and trans fats, which come with ceilings, the evidence generally treats this one as beneficial, so the goal is to make it a larger share of the fat you eat.
Its value shows up mainly in what it replaces. When monounsaturated fat takes the place of saturated fat, that swap is associated with a more favourable cholesterol balance over time, which is why it sits at the heart of eating patterns like the Mediterranean diet.
The best sources are easy to build meals around: olive oil, avocado, and most nuts, especially almonds, cashews, and peanuts. On a roughly 2,000-calorie day, a reasonable share is around 33 g, though this scales with how much you eat. There's no upper limit or toxicity ceiling, since the aim is favouring it within your overall fat intake rather than capping it.