How good is Duolingo’s Spanish podcast for learning Spanish?

I have been using Duolingo for over a year now and I’m looking to start listening to a Spanish podcast to learn more but I’m not sure I understand how I can learn just by listening to Spanish. Can anyone tell me how to learn Spanish by using a podcast? Do I need to use another tool along side the podcast or am I meant to work out what the Spanish words are just by hearing them?

Any help and advice would be appreciated, thanks.