Tephrosia belong the pea family and that's clear if you look at their little hairy seed pods.
These are currently blooming in large quantities on the hillside and pink flowers are more noticeable because many wildflowers are yellow. Yellow flowers are most visible to bees and they are thought to be red-blind. Red flowers are pollinated by sunbirds and butterflies. This is too small and delicate a flower to be pollinated by birds and it isn't a very bee-friendly shape so it is likely that these flowers are pollinated by butterflies.
The legume family are known as nitrogen-fixing plants. Nitrogen usually enters the soil through a process of ammonia decay but some plants have a relationship with nitrogen fixing bacteria in their roots whereby the plants absorb nitrogen from the air and the bacteria convert it into plant-friendly forms or nitrates. Thus, legumes have a very important role in enriching the soil and and there are many different kinds of legumes growing in grasslands.