With this card we enter the third decade of the deck, starting with the Seven Liberal Arts which presented a canonical way of depicting the realms of higher learning. The sequence starts with the Trivium, the lower division of the seven liberal arts in medieval schools, consisting of grammar, logic, and rhetoric.
The tradition of depicting the Seven Liberal Arts as women dates back to Martianus Capella (5th century) and his allegorial treatise 'De nuptiis philologiae et mercurii libri novem'.
Grammatica, of course, represents grammar, but one has to remember that in the Medievals and the Renaissance grammar did not mean what it means today. It was not so much about learning grammer rules, but to grasp the language as a whole, to learn how words could be used to create effects, to strengthen expression and meanings. Grammar was the foundation of both philosophical inquiry and practice of virtue.
Grammatica is represented with a vase and a file - the vase contains medicine to cure the language and the file to rasp away the errors.