What are T$ and W$?

T$ are won by qualifying for either the $1 Million guaranteed tournaments held every Sunday with respective entry fees of 215 and 530. The is held weekly with the $1 Million monthly only on the final Sunday of each month. If you unregister from the event which you win an entry to, your account is credited with the respective amount of T$.

In order to earn W$ you can win satellite events to any WSOP, WPT, EPT, or WCOOP events. The same process must be taken in order to have your account credited with W$, unregister from the event and you will have the buyin for the tournament you unregistered from in W$ available in your Cashier.

An official explanation is provided on the PokerStars website

How do I know how much cash I will receive for my W$/T$?

Using the Exchange W$/T$ link on the left side of the page you will be directed to the exchange rate calculator. No matter what quantity you have to sell, I am happy to buy them from you.

Is the exchange process safe?

Since all exchanges are made directly through the PokerStars main lobby, it is 100% safe for both parties. Once identical requests are submitted by the involved players, the exchange is automatically made and the cash will be in your account at that time.