Need a more knowledge on connection pool

    try {
        sequelize = new Sequelize('test', 'postgres', 'root', {
            host: 'localhost',
            dialect: 'postgres',
           logging:false,
            pool: {
                max: 12,
                min: 0,
              }
        });
        await sequelize.authenticate();
        console.log('Connection has been established successfully.');
    } catch (error) {
        console.error('Unable to connect to the database:', error);
    }
}

here i try to understand the connection pool concept in sequelize with node js . here i define my database connection and define pool 12. i read docs and so many other recourses but picture is not clear in mind.

here max = 12 what exactly define ? number of connection which we made by Sequelize instances ? or some recourses say sequelize is create a new connection per query !! what exactly happen ?

and in every resource only theory explained . not showing single case when we got connection error due to busy all pool connections

thanks for answer in advance