Time spent studying and listening in the native language is the only way to improve your speaking ability when studying a language with completely foreign grammatical constructs.
if you're studying spanish as an English speaker, you could kind of just wing it, learn a bunch of words, and translate from english to spanish directly and get by.
But for korean since every grammatical structure is completely foreign, you need to study a lot, and you need listening exposure to ingrain it into your mind.
i have studied korean for 2 years, and have put in approximately 2,300 hours of study, and I can communicate fine, at roughly the level of a korean child.
But if you are thinking that you are going to pick up a textbook and read it and learn to speak, you need to realize that language doesn't work like that.
Learn 1000 words, spend 100 hrs or so reading easy sentences, and then immediately jump into listening activities by watching things that a 5-7 year old korean child will watch.
At first you won't be able to catch anything because you haven't learned the various ways that koreans can pronounce their language. Based on pitch and voice type the sound of the voice changes considerably.
anyway if you do listening without subtitles on easy conversation for 100-200 hours you will find yourself hearing more and more.
Transcribing what you hear is also a very good exercise. After listening to an episode of something, it is also good to go actually read the transcript to learn the phrases that you were supposed to hear but couldn't.
Anyway if you study using this kind of method then pretty much anyone will be capable of communicating at a child's level after around 1000 hrs of study.
Children study for 10 years while having nothing else they have to do, so of course they are good at their language. It's difficult for adults to make that kind of time, so many think that older people can't learn a language. The age is not really the problem, the problem is that older people don't have the time and passion to learn a new language, especially if it is very different than their own.
Don't watch things with subtitles until you are confident that you can hear >90% of the episode without subtitles