Can you explain the problem with the statement
"the somatic nervous system controls mainly involuntary activities" to me?

It is called autonomic because it works on its own and it regulates organs functioning which is a thing that happens involuntarily. It regulates heart beats for example and it's not something that you do voluntarily since the heart beats regardless of you. It also controls things like vomiting or sneezing that you can't choose not to do when it starts happening.

» somatic and autonomic nervous are the part of peripheral nervous system

» somatic nervous system has two nerves cranial and spinal

» autonomic has two nerves sympathetic and parasympathetic

» the nerves of somatic that is of spinal nerve arises from spinal cord

» The nerves of autonomic nervous system are concerned with same function as that of adrenaline

hope  this helps