Is it normal for a 12 year old boys testicals to breath?

The testicles do not breathe. However, the scrotum (the sac that contains the testicles) undergoes temperature regulation. To keep the temperature optimal for sperm production, the scrotum retracts toward the body when it's cold, and relaxes to hang further away from the body when it's warm. This process is normal and does not require any treatment or intervention.