Assuming it's a TSH of 11.8 it suggests hypothyroidism. Would repeat it a few weeks after the first test to confirm before committing to medication. Also need to determine the cause of the abnormal lab -- ie, hashimoto's thyroiditis vs transient thyroiditis vs lab error vs other cause of low thyroid, etc.
It means you will need to take thyroid medicine. What has your Dr. told you. Mine was 20 last week so my meds were increased I take Levoxyl. The reason mine went so high in my opinion is because I stopped taking the Levoxyl for a month or so. Felt lousy so had my blood tested and voila! Now I return in 6 weeks for another blood test to find the numbers. Maybe I will stay on the dose or it may need to be adjusted. This was my fault for stopping. They told me they like mine around 2.5