Vocabulary...
You need a lot of it, but sometimes it feels like you have none of it (insert cry emoji here). The worst thing? Often our vocabulary is less than stellar in our native languages, so building an entirely new lexicon can seem overwhelming . And it is a challenge, no doubt . But you can do it! The only reason it ever seems impossible is if you try to learn too many words at once, or words that you never use and never hear native speakers using. Unfortunately, that's often the vocabulary we are encouraged to learn by teachers and the text books they use.
That's why it's so important to learn the English that is essential for your own life, work, and interests. Don't just copy other people's vocabulary, or assume that you need to memorize every word – nooo! I promise you, that strategy never ends well. Slow and steady wins the race , and being picky about what vocabulary you learn, and how fast you learn it, will ensure many meaningful English conversations in the future!