Where can I edit stock item with a spelling mistake ?

Hi fredthecob - welcome to the Community. 

You can edit stock items from your product & services list (select the Cog in the top-right of QuickBooks > Lists > Products and services). From here, select Edit in the action column beside the relevant product to make changes. To see more on how to add, edit and delete product and service items in QuickBooks Online, click here.