Specify the child entities (the entities referenced by this entity) that should also be cloned as part of the cloning process. If they're not included, these fields' referenced entities will be the same as in the original. In other words, fields in both the original entity and the cloned entity will refer to the same referenced entity. Examples:

If you have a Paragraph field in your entity, and you choose not to clone it here, deleting the original or cloned entity will also delete the Paragraph field from the other one. So you probably want to clone Paragraph fields.

However, if you have a User reference field, you probably don't want to clone it here because a new User will be created for referencing by the clone.

Some options may be disabled here, preventing you from changing them, as set by your administrator. Some options may also be missing, hidden by your administrator, forcing you to clone with the default settings. It's possible that there are no options here for you at all, or none need to be set, in which case you may simply hit the Clone button.

Entities referenced by field Program podróży (field_program_podrozy).
Entities referenced by field Termin/Cena (field_termin_cena).