There are special sign language training institutions. I remember there is a sign language school near Zhongshan Park in Changning District. However, only you can understand sign language, even your brother can understand it.

If you can't find this sign language school, you can also go to the district and county disabled persons' Federation to learn about the situation and let them introduce the place to study.

In terms of welfare, you can apply for disability appraisal for your brother, one is hearing disability, the other is intellectual disability, and there may be some financial subsidies such as subsistence allowances. However, not everyone has it, depending on the family's economic situation. However, there is always a disability appraisal. You can contact the street assistant directly for relevant information.

Your brother is glad to have you ~ ~