You can use normal copy and paste functions in Zenkit to transfer text or numbers between cells.
Select the text or number you'd like to copy, then click Ctrl+C. Navigate to where you'd like to paste it, then click Ctrl+V.
As well as duplicating within a collection you can also copy an item to another collection. To do so click the "..." symbol on the expanded item panel, click "Copy to collection" and choose the collection you want to copy the item into.
Because the fields may vary in different collections you will be asked where the field of the copied item should be transferred into inside the new collection.
To learn more about shortcuts in Zenkit.