If you took a year or two of a foreign language in high school, you probably know a few common phrases and some basic grammar, but you probably would have a great deal of difficulty communicating fluently in the language. It's not your fault, you may have studied quite hard. The reality is that method of learning does not work, in the sense that it can't make you fluent, just as learning to to read music won't make you a composer or a performer.
Our brains are not computers. If I say the word 'Grandmother', your brain doesn't perform a lookup in some database table to find a definition for Grandmother. You brain more than likely has deep associations, patterns burned into your neural pathways that form complex, perhaps deeply emotional memories about your Grandmother. Maybe she has passed. Maybe she is still with you and enriches your life. Maybe you can't stand her (I hope not.) Either way if I asked you to reflect about your Grandmother and how you feel about her, but use the word Abuela instead of Grandmother to refer to her, that word would eventually (if you revisit it enough) become associated with your Grandmother (the person, not the word), but not just in a left-brain, look it up in a table sense, but also in a right-brain and emotional sense. You will 'know' that word (or Grok it as Heinlein would say), in a holistic way.
Being fluent isn't about doing translations fast in your head on the fly. Your brain is not fast enough to do that well. It is about words and the ideas they represent being inextricably linked, being one and the same, and that mental representation includes a complex web of memories and emotions.
Why do I keep talking about emotion? Well, think about it... what happens when you try to learn something that really interests you? How do you feel when you do that? How easy is it to learn something that excites you and fascinates you? It isn't hard. What about the opposite, something that you couldn't care less about? A dry book on some technology you have no intention of using for example. Your brain will have a really difficult time burning durable memories of what you're taking in. Your brain wants to remember things that it thinks are important, and if it isn't triggering any emotion on some level, it isn't important to your brain.
A brilliant teacher in Minneapolis named Luis Rojas uses what I consider a clever hack built around this idea to shovel understanding of Spanish language into the brain. In his podcast he doesn't do vocabulary drills or grammar lessons. What he does is simply talk, in Spanish. His grammar is not very advanced, but it does require some basic Spanish understanding to follow. What happens though, when listening to the lessons, is a kind of slight of hand where he distracts the listener from the fact that he is teaching, in a way that allows the words he is saying to become tied to emotional memories.
How does he do that? He paints a picture of events in his life that have emotional resonance for him. Seeing the email on his phone from his brother saying don't worry but he is in the hospital for a cardiac event. He knew reading between the lines that it was serious because his brother was a cardiologist and wouldn't contact him if it was something routine. Most of us have received some kind of email like this where the subject line puts a pit in our stomach. The telephone ringing at 3am feeling. In another podcast, sitting at his computer on a cold blustery Christmas eve, listening to the wind and the creaks of the house while his wife sleeps and he reflects on Christmas of the past, gatherings with friends from his past, and hopes and plans for the upcoming year. His speaking style is warm and conversational, like you and I would talk about our lives. Interweaved with the speaking is music, songs that were popular at the time of the whatever he is reflecting on, or just quiet piano music. Many of the songs are ones I associate with earlier times in my own life (music is very effective that way as a soundtrack for you life.) In doing this he conveys not just a message, but an emotional state.
The synergistic effect of his almost hypnotic delivery, the subject matter, and the music is it triggers memories of things in my own life that I've experienced. This creates a relaxed mental state where the left-brain isn't trying to catalog and store words for later recall, but where the words are being bound up with my own emotional memories. The end result? I forget I'm listening to Spanish. He might as well be speaking in English. It's like a Spock mind-meld. This cements a context and an understanding of the words well beyond what simple memorization would accomplish.
If you're learning spanish, check out his podcast at http://www.lacasarojas.com.
Oh... and call your Abuela..