Hive is a data warehouse system that provides data analysis using SQL-like queries. It allows querying and managing large datasets stored in Hadoop. Hive uses its own query language called HiveQL, which is similar to SQL. HiveQL supports operators for relational comparisons, arithmetic operations, logical operations, and operations on complex data types like arrays and maps. The seminar presented an introduction to Hive and HiveQL, differences between Hive and relational databases, and details of various HiveQL operators and their usage.