What does this regular expression mean?

I am doing the Titanic test and found that the meaning of such a code is not quite clear
1 Why is there a number in the first one, please tell me what does it mean
2 Why? + means to repeat what does it mean by using two
3 regular expressions?
Thank you for your answers. Thank you,

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Ide cPP java python javascript
Mar.18,2021
  1. A comma is a match for a comma.
  2. + means at least one,? Represents at most one
  3. ^. +? If it is a lazy pattern, it matches any character.

comma is not a metacharacter. It should match a ,

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MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1ea404f-1c9c.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1ea404f-1c9c.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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