The offline measurements (measurements made without the application open on the account) are automatically synchronized when the user reconnects the scale to his application.
Synchronized results can be viewed in the results list: MENU > Weight > List.
The icon indicates the offline measures that have been synchronized successfully.
Synchronized results are automatically deleted from the balance memory.
*credit to Sylvain of iHealth Labs EU
https://helpcenter.ihealthlabs.eu/hc/en-gb/articles/360003867278-iHealth-Fit-HS2S-Synchronisation