I came across this expression on the internet, but what exatly is a homeroom teacher, can someone please explain it to me?
The only thing I could find was that it's some sort of "social" teacher with whom the students have contact a few hours/week.
That's right. It's a teacher that has a certain class assigned to him/her and he/she looks after that class in terms of organizing special events, collecting fees for some activities that the class might be involved in. Homeroom teacher always meets with the class at the beginning of school year to help "his" students find themselves around in terms of new classrooms, meeting new teachers, etc. I had my homeroom teacher meet with us once every three to four weeks. It's a good way of putting it...it's a social teacher. He/she makes sure that everything runs smoothly.