Which natural resources are called the “biodiversity hotspots”? How do these hot spots maintain ecological balance?

Hint: Biological diversity refers to the variation among living organisms from all sources, including terrestrial, marine, and other aquatic habitats, as well as the ecological complexes to which they belong; it comprises diversity within species, across species, and within ecosystems. In simpler words the more the variations in species of living organisms the more will be the biodiversity of a particular area.

Complete answer:
The term "biodiversity hotspots" was coined by Norman Myers and refers to areas noted for their high species richness and endemism. and species richness. To be considered a hotspot, a location must meet the following two requirements, according to Conservation International:
There should be at least 1500 vascular plant species in the region, indicating a high degree of endemism.
Species must comprise $30\%$ (or less) of its original habitat, implying that it is endangered.
Ecological balance can be defined as the equilibrium between, and harmonious coexistence of, organisms and their environment. It indicates the ability of an ecosystem to return to its original state following a disturbance. It is widely held that the greater the diversity of species within an ecosystem, the stronger it is and the more equipped it is to withstand external disturbances.This is because species in an ecosystem rely on one another for food,in the form of a food web. If there are a large number and variety of species in a food web, the extinction of one species for whatever reason will have less of an impact on the ecosystem as a whole than if the extinct species served a key function on which other species relied exclusively.
Therefore biodiversity hotspots in an ecosystem, that is a large variety of species and genes in the ecosystem contribute to a stronger ecosystem.

Note:
Biodiversity Hotspot zones are home to a diverse range of remarkable plant species and habitat, but they are also threatened by endemism and habitat degradation. As a result, it is our responsibility to safeguard and conserve endemic species and their habitat. Four out of the 36 Biodiversity Hotspots in the world are present in India: the Himalayas, the Western Ghats, the Indo-Burma region and the Sundaland.