stopwords, and 2-character and smaller words are excluded
This is the default. It can be changed from the Settings page. The settings can be adjusted from both the Word list and the main pages. One can look at the list of stopwords.
Consider the following counters from the current collection.
Total: 1820, Word count: 5599, All words count: 8376
1820 is the Total number of unique words (without the excluded ones).
Word count of 5599 is how many times these words are used.
All words count of 8376 is the count of all words (including the ones discarded from the list).