The levels of fluency in a language are as follows:

Any character who starts with a language that is ubiquitous in their areas starts with it at Native. Any character who starts with any other language starts with it at Fluent. Without speaking it from birth, you must speak a language regularly fluently for 10 years to speak it at a native level. Some languages, such as elvish, have noticeable differences between a native and fluent level of speech. Moving from accented to fluent is not a matter of learning; you can become fluent by speaking the language regularly for at least 6 months. Otherwise, you will remain at accented.

The time taken to learn languages varies wildly. However, if the student has bonus languages due to a high intelligence that they did not spend during character creation, they can pick up a language very quickly - a character with an average intelligence will advance through the early stages in no more than 2 weeks apiece, and even the later stages will pass within a month apiece. With a high intelligence, they can easily be even faster. If they do not have a free language slot, learning a new tongue can be difficult. It depends on many factors, including: complexity of the language, intelligence of the student, quality of the teacher, regularity and time dedicated to teaching, whether they know any languages with similar roots, and how many languages they have picked up in the past (the more languages you learn, the easier it becomes to learn new ones). For a language of average complexity (Common), with an average intelligence (10), with an average teacher and spending a few hours each day on its study, the early stages can be mastered in a month apiece, while the later stages may take up to 4 months each to bring up to accented.

Human & Demihuman
Common Spoken by men of Vingaard, Lorknir, Warden and Kharolis
Vintish The formal language of Vingaard, used in old texts and official ceremonies.
Andruan Knife-Marks The oldest known human language, originating in the Plains of Dust.
Norse The language of Nordmaar.
Elvish The language of elves: dialects include Auld, Leng, Sea and Frost.
Dwarvish The language of dwarves. Closely guarded; speech by a non-dwarf is a grave insult.
Gnommish The language of gnomes.
Undercommon A language of hand signals and gestures developed by the Drow of the Underdark.
Karpathi A very old language still spoken by the barbarians of Qolor and the Borderlands.
Shalafi A sister-language to Karpathi, spoken by the nomads of the Plains of Dust.
Tengu Spoken by the tengu tribes of the Plains of Dust.
Druidic The sacred language used by druids and rangers of the Circle.
Thief Cant Half-slang, half-code used by thieves to communicate.
Mercenary Cant A bastardised combination of words from many language, common in war camps.
Nirrinese Canticle A secret tongue used by the Cult of Nirrin.

Tongues of Power

Not all languages are simple modes of communication. Throughout the planes, there are tongues both old and powerful which are inexorably tied with the mystic underpinnings of the universe. These languages are so powerfully magical that they defy the very mind that attempts to comprehend them, requiring a Read Magic spell to easily parse them. Casting Read Magic does not grant comprehension of a magic tongue, however - in order to read a writing in Draconic, you must know Draconic and cast Read Magic. Once a particular magical writing has been read with Read Magic, the wizard can easily read it thereafter without additional castings of the spell.

For more information on tongues of power, see the relevant page.