This would technically be a rules question and need to go under the rules forum so they can be answered by Tori, Steve or James, but I’m going to just give you page numbers to go look at in the new rules to hopefully save both you and them time. I’d suggest reading the whole section of each of these pages, and if you still have questions after that, you can post it on the rules forum.
Page 7 of the new rules:
Additionally, all characters gain access to their culture’s literacy for free; Anterran for Humans, Deurgan for Hillfolk, Faeryhen for Faeriekin, Tyrelian for Elves, Kaejish for Katta, and Vardakk. Information on Literacies may be found in the Ability Supplements section of Chapter IV.
Definitely also read all of page 167, because it has all the rules around Literacies, including
Note that there is no spoken language mechanic at Knight Realms. The skill Literacy does not grant the character the ability to speak the language, nor does any other skill.