Currently the production queue progress is shown by a percentage, which is not that useful. In the top left picture below, we see that the four units are 56% complete. But how does that help us? What we really want to know is when these units will be ready.
In the top right picture I've changed it to show the time remaining. Now we know that the four units will be done in 14 seconds. (The green overlay gives us a rough indication of the percentage anyway.) The timer counts down so I think its meaning will be obvious to users.
Pictures here if they aren't shown above.