Understanding How to write test data in Robot Framework - robotframework

Question

I am new to Robot Framework and going through its documentation. In Robot Framework's overall test data syntax they state the below example:
*** Settings ***
Documentation Example using the space separated plain text format.
Library OperatingSystem
*** Variables ***
${MESSAGE} Hello, world!
*** Test Cases ***
My Test
[Documentation] Example test
Log ${MESSAGE}
My Keyword /tmp
Another Test
Should Be Equal ${MESSAGE} Hello, world!
*** Keywords ***
My Keyword
[Arguments] ${path}
Directory Should Exist ${path}
I am unable to understand what [Documentation] / Example test and [Arguments] ${path} in respective sections means - there does not seems to be a clear explanation for same?
How can I learn these basics syntax as the guide does not starts from basic "Hello World" program?

Answer 1

Overview
Values in square brackets in a test case or keyword definition are called settings. They are documented in the robot framework user guide in the sections titled Settings in the test case table and Settings in the keyword table.
Robot supports a fixed number of settings, so you can't just put any word you want inside square brackets. Anything in the first word of a line that is in square brackets will throw an error if it's not one of the supported settings.
Test cases support the settings [Documentation], [Tags], [Setup], [Teardown], [Template], and [Timeout]
Keywords support the settings [Documentation], [Tags], [Arguments], [Return], [Teardown], and [Timeout]
[Documentation]
As you surmised, [Documentation] is for setting the documentation for a test case or keyword. More information can be found in the robot framework user guide, in a section titled Test case name and documentation and User keyword name and documentation
The advantage to using [Documentation] instead of comments is that the documentation will appear in reports and logs, and will be included in documentation generated by libdoc and testdoc.
[Arguments]
[Arguments] are how you specify arguments to a keyword. You cannot use this setting for test cases. It is only available for keywords, and is documented in a section titled User keyword arguments
For example, if you write a keyword that accepts the arguments "first_name" and "last_name", you would define the [Arguments] setting like this:
*** Keywords ***
Example Keyword
[Arguments] ${first_name} ${last_name}
log Hello, my name is ${first_name} ${last_name}
Within the keyword, the first argument will be assigned to the local variable ${first_name}, and the second argument will be assigned to ${last_name}.