Explained in detail here
What kind of posts you can expect :
Personal Clerks, Steno Typists,Assistants in various departments,… Please refer to the government notification for more details.
NOTE: TNPSC Calendar for 2019 mentions that the announcement for the 2019 prelims is expected to arrive in May.
NOTE: All the above information is from the last year notification issued by the government. Do take a look for intricate details. The notification for this year exam is the only authentic place to find steadfast details for the next exam. Kindly use the last year’s notification (given below) as reference.
Last Government Notification:
Click here for the link