There are four main skills that a language learner is trying to master: speaking, listening, reading, and writing. For most people, speaking is the main focus. They try to connect with native speakers, so they could practice what they've learned. They read because they want to learn more words, so they could speak. They write because they want to get more confident in grammar and word use, so they could speak better. As for the listening and comprehension part, that's when things get messy.