The nation's tata is simply a slang term for a breast that, although it
may be a bit on the
small, or perhaps overly large side, is still leaning towards
average. You might say that a breast that is the nation's tata is still easily squeezable, played with, etc.
Although my chest isn't that big, I'm
still nation's tata.
Although I surprisingly wish I was a
bit smaller in the chest area, I'm still nation's tata, so it's not that much of a
problem.