You got most of this during the episode, but each 'Age' (as tracked by the Chantry Calendar) is 100 years, and is named based on signs witnessed by the Divine in the 99th year of the previous age. There have been 9 ages since the founding of the Chantry calendar, and this is the first number in the Y:XX dating scheme. Saying the number and the name of the age is a bit redundant. The second number is the year in the age. So saying 4:33 is the 33rd year of the 4th age. The ages have been Divine, Glory, Towers, Black, Exalted, Steel, Storm, Blessed, and the game takes place in the 31st year of the Dragon age, so you're currently in 9:31. Anything that happened before the Divine Age is called the 'Ancient' Age and the numbers are tracked backwards, so -350 Ancient is 350 years before the beginning of the Divine Age.