(Don’t worry - all ‘hosts’ have instructions on how to get your podcast listed in these places).
Your ‘host’ is the company you will upload your audio to. They then process it and keep it on their servers to deliver your podcast to whoever wants to stream/download it. Your host creates the ‘RSS feed’ that you submit to Apple Podcasts, Spotify etc. (Don’t worry - all ‘hosts’ have instructions on how to get your podcast listed in these places).