Wiktionary
a. (context idiomatic informal English) speaking about, talking of.
Usage examples of "on about".
And he keeps on about these anomalies which I know from my own experience aren't there!
The Buddha just babbled nonsense, and Confucius wouldn't stop droning on and on about filial piety.
Kemmerich is dying, and Muller rattles on about Kemmerich's stolen watch and just who will get Kemmerich's fine English leather boots.
When Weary rambles on about different kinds of torture, he's speaking in the abstract, not talking about torturing anyone in particular.
Third had ranted on and on about the dangers of such a concession, then glared at Todd to make the translation of ten minutes of rebuttal.
I babbled on about the beach, the weather, the housekeeper, my friends.
It's too neat to be mere coincidence, especially when all the figures match all that incriminating junk Rogitel was waffling on about.
He didn't lift his eyes to ask, 'What's this group yo's on about then?