Python developers using PyMongo can create a new database and collection by importing the pymongo library, creating a client object, and then using the `insert_one()` method to insert a document into the collection. The database and collection are created lazily, meaning they are only created when a document is inserted. The `_id` field is automatically generated for each document and is unique across all documents in the collection. The generation time of an ObjectId can be retrieved using the `generation_time()` method.