The red one is a male and the greyish one is a female.

Very good mr Gnib_jr :-)

Then what is this one?

A male??

It’s both male and female. Look up halfsider parakeets if you want to know more.

oh, cool!

Yeah, it’s really interesting

but how do they reproduce?

They don’t. It’s a mutation where two embryos fuse early in development.

oh ok

It’s not necessarily male/female or two different colors, it can be the same color and gender making it almost impossible to spit.