Hey!
I'm currently a first year OT student. The first year of my program is focused on mental health, so I'll try to help you out as best as I can.
From what I have learned so far, OT's in mental health help people suffering from any type of mental disorder perform their occupations. For example if someone with mental ******ation is having difficulty performing meal preparation an OT will form some type of intervention which involves educating the patient on how to prepare their own meals/food. This would include something like preparing a chart with pictures of how to cook, visual or verbal cues, etc.
If an OT is working in a hospital or rehab they can also run different activity groups. I did my level I fieldwork in a psych ward of a hospital. The patients were diagnosed with bipolar, schizophrenia, depression. The activities were educating them about proper health, how to have a positive attitude, exercise. Then I also did some type of activity to engage the patients and help them interact with one another. Starting my level II in a couple of weeks (!!!!!!!)
I don't know if an OT does "counseling". I think that is more of what a social worker would do- the OT is actually doing therapeutic interventions to help the patient live as normally as possible.
Hope I helped! GL!