the database you're connected to doesn't have the HR schema?
those are put down at install time if you choose to include the sample schemas
Please post in English as that is the language of this forum.
Only guessing based on what the other responder posted:
1. If your question relates to a database post the name and full version
2. If your question relates to a connection in Sql Developer post the full version of Sql Developer and the info you provide in the connection dialog
3. If your question relates to 12c and HR then maybe you are connecting to the root/CDB instead of the PDB where the sample schemas are located.
We can't help you until you provide the info we need to do that.
Might not be the case if using XE.
Depending on your DB version, look for the "Database Sample Schemas" on the documentation (example below for 10G), there is usually a section on manually installing them which provides the creation scripts.