How to release a person who wrongfully admitted to selling drugs?

My friend got arrested in Dubai while he was using drugs. His friend was also caught by CID for selling drugs. After questioning them, my friend accidentally agreed he was selling drugs.

Because he is not good at English and Arabic. It’s been six months since they got arrested. Now, the case status is that he was selling psychotropic substances and it’s a huge amount (almost 20 grams of MDMA).

So what will the punishment be?