I Listened to a podcast, in which the speaker attempted to explain what тренироваться на кошечках means and how it's used, yet I failed to grasp the meaning. Can someone explain?
Means "to train on a dummy" or "to practice the skills on a much simpler case".
Having been born back in the USSR and still being widely used by all generations, except may be the very old, it's quite a resilient meme from a film called "Операция Ы". Here's the scene where it's used: link.
It can be employed quite liberally in all sorts of conversations -- you can have a dialogue that goes like this:
-- Давай поднимемся на Эверест?
-- Может, сначала потренируемся на кошечках и покорим Эльбрус?
The only useful form in spoken language is direct movie citation: "тренеруйся на кошках".
Source is this movie, this episode: https://www.youtube.com/watch?v=s9aJqeeNVBQ
When this phrase could have a meaning "to train on a dummy" in real life dialog it is always a joke and almost never used for something else then friendly bulling: "you have no skill, find other fool :P".
Also to hear it you should directly trigger word "тренироваться": "я тренирую..", "я собираюсь тренивать.." .
E.g. playing chess with a friend, if you would comment you first moves: "this time I'm going train my King's Gambit" you would get back "тренируйся (лучше) на кошках" probably nine times out of ten.