SQL - Is a STRUCTURED QUERY LANGUAGE which is mainly to used to interact with the following RDBMS databases such as: Oracle DB2 Sybase Microsoft SQL Server MySQL PostgreSQL etc.
RDBMS - Relational Database Management Systems. These Databases are collection of related tables. Example - SALES_DB this database by name contains all the tables in relation with the sales. They can be sales tables, payment tables, vendor tables etc.
TABLE - Collection of COLUMNS and ROWS.
DATABASE - Collection of TABLES.