SQL Vs MySQL vs MongolSQL I've recently been doing a SQL course and I’m finding it incredibly easy to read.

If I can read SQL and write in it, could it be possible that it’s almost the same to MySQL and Mongol SQL? Just some clarification would be great.
Yes and No. Most of the RDBMS  like MySQL Postgres SQL-Server ... relay on the basic SQL Syntax. All the different systems have their own dialect with their one extensions on SQL but it is rather easy to transit between the individual ones.

MongoDB is somewhat different as it is a so-called NoSQL ( Not Only SQL). Mongo ( like CouchDB or Cassandra) aren't based on the premises that your data is structured and store them in key-value pairs ( I have to admit I'm not an expert here, so correct me if I'm wrong) instead of tables.