The 'component' is the part of Moodle that this task belongs to.
e.g. 'core' is tasks that are part of the core Moodle functionality
'mod_forum' is tasks that are part of the 'forum' activity in Moodle.
The 'classname' tells Moodle the name of the PHP class that has the code to run that task. These are stored using PHP namespaces, to allow the correct code to be automatically loaded.
All 'core' tasks are found in the /lib/classes/task folder in the Moodle code.
All other tasks are found in the relevant plugin, e.g. 'mod_forum' tasks are found in the /mod/forum/classes/task folder, 'enrol_ldap' tasks are found in the /enrol/ldap/classes/task folder.
The filename for the task will match the last part of the 'classname' - e.g. \enrol_ldap\task\sync_enrolments will be found in /enrol/ldap/classes/task/sync_enrolments.php
'Blocking' means that the task will block all other tasks from starting whilst it is running (normally different tasks can run in parallel) - it is defined in the db/tasks.php file for each plugin and normally doesn't change.
'faildelay' is how long a task is delayed for if it throws an error during execution (this is so that the delay can be increased each time, to avoid a failing task being called too often).
'customized' records if you've gone into the admin settings page for the scheduled tasks and changed the default schedule for the task.
As for the long list of different tasks, you would have to open up the code for each one (based on what I've written above) and read through the comments in the code in order to understand exactly what each task is doing.