so im rebuilding my brakes and when i tried to take the brake plate off oil started draining out of the bearings. i thought that bearings were packed with grease. What kind of fluid is in there and how do i replace it when im done working on it?

its a 4 speed swing axle manual trans 68 beetle

 

That is Transmision Oil. You have to replace the outed seal. Get a real axle seal kit and it will come with all the part that you need to change (cheap and easy)
After you clean all the area with brake cleanner. Check the level of your tansmision oil or just change it to while you are there.