I'm sorry you're feeling so frightened dear! Don't be! People are here on BB to support you.
Ok I worked in a psych unit but emphasise I have no forma qualifications as such. I looked up psychosocial therapy but it's pretty self-explanatory. So don't be scared it might be just the thing for you.
I think it's just helping you look at what things make you fearful, understanding your anxiety better and how to deal with it, and helping you to deal with social situations. Probably they might get you to talk with a group. These people will be supportive and also needing the same sort of help as you. They might get a nurse or social worker or counsellor to help you with any problems you have with mixing with other people, or family issues, or anxiety/depression.
It really just means they'll be looking at any mental health issues you may have, and also any difficulties you have with mixing with other people and/or your family, and helping you find ways to cope better with situations that make you anxious. That's the understanding I have of it. Someone else may come on with more information for you.
We used to have patients attend groups for this sort of thing as outpatients, (meaning they stayed living at home and just turned up for their therapy sessions) or maybe because the hospital is a long way from you they might want you to stay with them for a little while because of the travel distance. I'm not sure from what you've said.
You might get help from a psychiatrist, a social worker, a psych nurse. They're all there to be supportive and help you. So it's nothing so scary. It could be a great help for you, especially as you're lonely and people are excluding you in the town where you are.
So try not to be so frightened, they perhaps should have explained better to you what they meant by the word! It's not scary. It's just looking at every problem you might have - mental health issues, social problems, family problems if there are any, and trying to help you deal with all of them. You'll be fine. So I know you've been badly frightened but it will be OK and might help you a lot.
I don't know if this helps but I hope you'll be less frightened now. Truly it's nothing so scary as you're thinking at the moment! It's meant to be supportive and helpful.
I truly hope you feel less frightened now and realize they're truly trying to give you some good help. Hugs from Sam and me, you'll be absolutely fine! HUGS, HUGS.