To do well in the world, and to try to make sense of it, we all need to communicate effectively. Talking and listening are crucial parts of good communication.
If you hope to go to university you will need these skills in tutorials. In tutorials you will be expected to put forward opinions, challenge the opinions of others, put forward alternatives, all within discussions.
Most jobs nowadays require very good communicating skills. Even trying to get a job in the first place involves an interview where you have to put forward a good impression of yourself by talking and listening.
Talking and listening are essential communication skills and that is why they are part of Higher English. For example, talking and listening (that is, discussing things with your teacher and your classmates) can help you to understand key aspects of the course - such as the literature you are reading.
To sum up:
Isn't spoken language just something you can do, or you can’t do?
No, it is something you can learn. There are techniques to follow and this guide will help you to improve/pick up some of these.
If you remember and use a few basic techniques, you will be successful in spoken language, and will be more likely to be untroubled by nerves.