What do History from and Last synced mean?

They are facts about your store that come from the sync. You find them at the bottom of the Store details card, in Settings under Store. You cannot edit them. There are four.

Shopify store is your shop's address, the one that ends in .myshopify.com. Click it to open that shop's Shopify admin in a new tab. It says Not connected when no store is connected.

History from is the day of your oldest imported order. Your P&L, your profit and loss statement, starts on that day. It shows a dash until your first import has finished.

Orders in the P&L counts every order in your P&L, from the first day until today. Cancelled orders and test orders are left out. It is Gross Orders, line 8 of your P&L, added up over all time. Last synced says when nouz last finished reading your Shopify store, for example Today, 06:00. The time is in your store's timezone. Before the first sync it says Not yet.

Under the card sits Delete store data, which removes this store's synced orders for good.