MongoDB has databases, collections and documents. These are analogous to databases, tables and rows in a SQL / tablular database. Then there are indexes and views which are similar to that of the SQL databases.
You can inquire into an installation for these objects. Typically, using a client tool. The main client is the command-line
mongo shell. You can query the data definitions as well as the data using commands or methods. Here are the shell methods, which includes the administrative methods: mongo Shell Methods.
The shell methods can also be run as commands: Database Commands.
You can also use the MongoDB Compass GUI tool to view the databases, collections, document structure (field types, etc), and indexes. For example view databases: Compass - Databases.
You will find this useful: SQL to MongoDB Mapping Chart.