Hello and thank you for the message!
I will answer in English - hope that's okay.
There are some options for English courses targeted especially for foreigners/immigrants/refugees. I'm not sure in which city your son would prefer to study, but here are some options in the Helsinki area:
Metropolia University of Applied Sciences, language courses
Metropolia also has some information targeted especially for Ukrainian refugees, you can check it out here
Finnish courses, you can search for different locations
I hope these tips will help you find a suitable course! You can always message us again to ask for help.
Have a lovely day!
Kind regards,
Emma, studentum.fi