What does prompt,set feedback in Oracle Export data mean?

prompt
Display the following prompt, equivalent to the general operating system command echo, output the following information importing table T_test
Set Feedback off

1. Set Feedback

There are three ways of doing this:

Set feedback on

Set Feedback off

Set Feedback n

By default, when a SQL is issued, Oracle gives a feedback, such as when creating a table, if successful, the command line returns a similar:table created feedback, or when a PL/SQL succeeds, the command line returns:pl/ SQL procedure successfully completed . When running many statements in a script, feedback is generally set to off.

Set Feedback N: When an SQL statement returns n or more than n rows of records, there will be feedback, for example: Set feedback 5, when the return record equals or more than 5 rows will have a similar 8 rows selected. Feedback. If the return row is less than 5, there is no feedback.

Set Define Off

The default "&" in Sql*plus represents an alternative variable, that is, Sql*plus will ask you to enter an alternate value whenever the symbol appears in the command. This means that you cannot enter a string containing the symbol into a database or assign to a variable, such as the string "Sql&plus" system will be understood as a string beginning with "SQL", it will prompt you to enter the value of the alternative variable Plus, if you enter ABC, then the final string into " Sqlabc ".
Set define off this function, "&" as a normal character, as in the above example, the final character is "Sql&plus"

Set define off override variable function
Set define on to open alternate variable function
Set define $ (not alphanumeric and whitespace) will override the default variable marker & as "" The original & flag will be inserted as normal characters, and "the original & flag will be inserted as normal characters, The following character will be the variable, and you will be prompted to enter it.

What does prompt,set feedback in Oracle Export data mean?