Finding oracle physical database files
An Oracle database instance is made basically of three kinds of files: database files (aka datafiles), controlfile, and redo log files.

You can check their names and paths by issuing these simple queries, logged with a DBA privileged account:

select name   from v$datafile;
select name   from v$controlfile;
select member from v$logfile;


Your question is a very newbie one. No problem with it, of course, but you should take a read on Oracle Database Concepts manual.

https://docs.oracle.com/database/121/CNCPT/toc.htm