What does galleon mean in English?

Could you please clarify for me the meaning of the word "galleon" in English? I've come across it in a few contexts, but I'm not entirely sure of its precise definition. Is it related to a type of ship or vessel, perhaps? Or does it have a different significance that I'm not aware of? I'd appreciate it if you could provide a concise explanation of the term and any relevant contexts in which it might be used. Thank you.