Tribunals are teams of specialists in particular areas of law who can make decisions on some disputes in that niche.
For example, employment laws handle most disputes between employees and their employers. Tribunals are less formal than courts, and the people making the decisions can talk directly to both parties in the dispute just like mediation groups.
These also handle land disputes, for example, disagreements about the value of land that’s being bought under compulsory purchase orders. Social Security Appeal deals with claims by people that they’ve been unfairly refused welfare benefits. The Immigration Appeals handle immigration cases.