In many cases the accommodation is very simple often on the floor or in tents. In case of lack of space some projects provide only one room together for males and females as accommodation. If you object to this let them know as soon as possible to arrange other possibilities. Participants come from many different countries. For the minority English is the mother tongue.
Many young people know some English from school.
You do not have to be perfect in a second language. You should be prepared to communicate in all non-verbal and verbal ways, even in a language which you know only a little.