One baby bird came on my terrace today, what do you suggest I can do to save this baby? I think it is a pigeon. I kept it at a place other pigeons can easily see, but no other birds came around.
Depending on your country call a vet or a licensed Wildlife Rehabilitator. They will be able to tell you what to do and where to bring the animal. Taking care of a wild bird is not simple and needs experience which Wildlife Centres for example have. They will raise the bird and release it back into the wild.
Depending on your location (if you add that I might be able to find more specific information) locate an expert on bird rescue. The link for NYC as an example of what to look for https://www.dec.ny.gov/animals/83977.html
As the page for NYC states you can do this:
While you wait for further instruction [from a Wildlife Rehabilitator], you can create a makeshift nest for the baby bird in a small Tupperware container or a similar round dish, completely lined with layers of toilet paper that prevent the baby from touching the container itself.