What do I get For 9.99 charge per month

No -- you can listen to all of the 60 million Apple Music songs free as long as you have an active subscription.

Note that it is still possible to buy music from the iTunes Store and if you do that you would pay for that music. Your rights to listen to purchased music do not expire.

See the following for information about both options: Add and download music from Apple Music or buy music from the iTunes Store - Apple Support

Streaming of 60 million songs. See information in Apple Music - Apple

If you want to cancel, see instructions in See or cancel your subscriptions - Apple Support