ODI datastore is an object in the ODI metadata to describe the source and target.
Typically a datastore is representing a database table in a relational database.
ODI does not use “table” probably because the source and the target can also be a file, which may be in a csv format.
A datastore must be created under an ODI model.
An ODI model can have multiple datastores.
Just like a database table in relational database, a datastore can have multiple columns.