will the table be locked if 2 or more jobs start hitting the same table (the one needs to read and the other to write)?

NO!

One of Oracle Database's great strengths is:

Readers NEVER block writers

As the docs say:

Nonblocking queries

Readers and writers of data do not block one another.


https://docs.oracle.com/en/database/oracle/oracle-database/21/cncpt/data-concurrency-and-consistency.html#GUID-4BD4DFD6-DAEA-41B2-BB56-7135568F0548

will each subpartition act like a separate table?

Yes and no. You can perform many operations at the (sub)partition level. And you can limit DML operations to a single partition - provided you include all the partitioning columns in their where clause.

Will subpartition increase performance of the the query?

Maybe

Partitioning is a big topic - I suggest reviewing Connor's primer on this to help you understand it better

https://asktom.oracle.com/partitioning-for-developers.htm

If two or more jobs hit the same table, same business date but different subpartition will oracle execute the 2 queries in parallel (like they are two different partitions)?

Any two sessions can query the table at the same time. It doesn't matter whether they're reading different partitioning or exactly the same rows. Both can run in parallel.

You can also have two or more sessions writing to the table at the same time. Writers can block each other in some cases - the classic example is two sessions updating/deleting the same rows. It's common to have many processes writing to a table with no blocking though.