I am starting the learning of backend. I get confused when I learn the tools such as dataGrip, PostgreSql, pgAdmin, and mySqlWorkbench. Do I need to download all of them?
Can anyone please give me some clue that what are these tools doing?
No, not at all. postgreSQL is a database (and a very good one, you should download and use that one).
dataGrip is a paid product from jetbrains, as a tool to connect and run queries on multiple different databases.
pgAdmin is a free tool specific to postgreSQL.
mySQLWorkbench is a tool specific to mySQL.
So, in summary, assuming you chose postgreSQL as the database, you would download that one and pgAdmin. Also consider dBeaver community which is another tool that works with multiple different databases.
postgreSQL cotains a command line tool called psql, that you can use to work with postgreSQL but it is text based and you would want something easier to use. datagrip is good but paid, pgAdmin, dBeaver community edition are good choices.