Step 5 of 18 of the SQL tutorial. GROUP BY folds every row sharing a value into one, and an aggregate such as COUNT then reads each fold. The 2033 names fall into three languages: 1395 English, 629 German and 9 French. Change COUNT(*) to COUNT(DISTINCT compound_id) and you count compounds instead of names — all 541 have an English name, 346 a German one, 7 a French one. This is the first question Mango cannot answer.
It opens on the query SELECT language, COUNT(*) AS nb_names FROM names GROUP BY language ORDER BY nb_names DESC, which you can run and change in place.
Ask the same question of a chemical dataset in SQL and in Mango and compare the two answers. The database is a SQLite file your browser downloads once and queries locally, so nothing you write ever leaves your machine — which is also why the tool needs JavaScript.