Hello Swathy,
Reset basically reverts jetstream container state to the beginning of the last refresh/restore operation
E.g: After refresh or restore, we have 10 rows in "table A" around 9:00 AM. We did multiple operations on "table A", and now "table A" had 25 rows. When we click on reset, our container will revert back to the beginning of container timeline when last refresh or restore happened (9:00 AM) and you will see 10 rows in "table A".
So, reset will undo all your previous operations happened after the last refresh or restore.
You can also undo particular changes with restore operation too, by choosing the time before the changes and restore the container state.
Hope this helps.
Thanks