This unique skill is actually a diverse number of skills, one for each language your character knows. This skill is broken down as follows:
Apprentice: You understand basic phrases and can speak/read at a tourist level. understand basic phrases in this language, and can speak or read at a tourist level.
Trained: You have a moderate level of fluency and can comfortably hold longer conversations.
Advanced: You are fluent in this language and are considered a native speaker of the language.
Expert: You have an academic level of mastery in this language, and can conduct complex conversations in it.
Master: You are a master of this language, and can fluently write stories and poems in the language.
Legendary: You have a historic level of control over the language in question, to the levels of Shakespeare, Moliere, Dante and Cervantes.
SPECIAL: You start the game with Advanced proficiency in your first language, and Trained proficiency in English, if it is not your first language.
Some common languages for Characters to know include the following, broken down by language families are as follows (languages marked with an asterisks are ancient languages more known to scholars than used in everyday conversations). Note that, depending on your background, your character can reasonably know and learn any language spoken by modern humans, these are just suggestions to provide a jumping off point:
Algic: Algonquin, Arapaho, Blackfoot, Cheyenne, Cree, Mi'kmaq, Ojibwe, Powhatan, Shawnee
Amazigh: Kabyle, Shilha, Tuareg
Armenian: Armenian
Atlantic-Congo: Fula, Igbo, Yoruba,
Attic: Ancient Greek*, Greek
Austronesian: Hawaiian, Indonesian, Javanese, Malagasy, Malay, Maori, Tagalog
Baltic: Latvian, Lithuanian
Bantu: Kongo, Shona, Sotho, Swahili, Xhosa, Zulu
Cushitic: Afar, Oromo, Somali
Dravidian: Kannada, Malayalam, Tamil, Telugu
Egyptian: Ancient Egyptian*, Coptic*
Eskimo-Aleut: Aleut, Greenlandic, Inuktitut, Yupik
Finno-Lappic: Estonian, Finnish, Lapp
Germanic: Afrikaans, Danish, Dutch, English, German, Gothic*, Norwegian, Swedish, Yiddish
Indo-Aryan: Bengali, Gujarati, Hindi, Marathi, Punjabi, Sanskrit, Urdu
Japonic: Okinawan, Japanese
Koreanic: Korean
Kra-Dai: Thai, Lao
Iranian: Avestan*, Farsi, Kurdish, Old Persian*, Pashto
Mayan: Classic Maya*, Wasteko, Yucatec Maya
Mongolic: Oirat, Mongolian
Mon-Khmer: Khmer, Mon, Vietnamese
Na-Dene: Apache, Chipewyan, Navajo
Nilo-Saharan: Nubian, Luo, Songhay
Quechua: Ayacucho, Classic Inca*, Cuzco
Romance: French, Italian, Latin*, Protuguese, Romanian, Spanish
Semitic: Akkadian*, Amharic, Ancient Hebrew*, Arabic, Aramaic*, Ge'ez*, Hebrew, Syriac
Sintic: Cantonese, Classical Chinese*, Mandarin, Shanghainese
Slavic: Bulgarian, Czech, Old Church Slavonic*, Polish, Russian, Serbo-Croatian, Slovak, Ukrainian
Tibeto-Burman: Burmese, Sherpa, Tibetan
Turkic: Azerbaijani, Turkish, Uzbek
Ugric: Finnish, Hungarian
Uto-Aztecan: Hopi, Mayo, Nahuatl