The SLA Date Field is a custom field that is used to search for issues against their deadline assigned in the SLA Metric Field. The SLA Date field's content depends on the SLA Metric field's content.
Editing the SLA Date field allows you to change its Name (label), Description (Help text) and Search Template. More information is available at this link.
To edit a field:
The Description is the Help text that appears below the custom field when it is displayed in the Simple Search column.
Search Templates are responsible for indexing a custom field as well as making it searchable via Simple Search and Advanced Search (note that custom fields are not searchable via Quick Search). Every custom field type has a predefined search template, but you may select a different template using this procedure.
To view SLA Date field in your JIRA system: