The Editor Dashboard is the main place to see what entries need work of some sort on them.
The actual URL of this page will depend on the language, but will be something like:
The main thing to remember is the general aim is to keep all of the numbers as close to zero as possible. For example, in the image below you will see that 18 words are listed as without a themed lesson. By clicking on the number you can get to this list of words and add a themed lesson to them.
Therefore, whenever you work on Lingopolo, try and see if you can fix any of entries listed and reduce the numbers.