Google Sheets integrates with Jira by allowing users to import data from Jira into a Google Sheet, and also by allowing users to update Jira data from a Google Sheet. This integration is possible because both Jira and Google Sheets support the use of custom fields.
To import data from Jira into a Google Sheet, users first need to create a custom field in Jira. They can then use the Google Sheets Import mechanism to import the data from that custom field into a Google Sheet.
To update Jira data from a Google Sheet, users first need to create a custom field in Jira. They can then use the Google Sheets Update mechanism to update the data in that custom field from a Google Sheet.