Yes, that's right. Manatees, also known as sea cows, really do have fingernails.
They are large aquatic mammals, and therefore have the same internal bone structure as other mammals, very similar to that of humans.
The eyes of manatees don't blink up-and-down like ours, though. They actually open and close in a radial motion, similar to that of a camera shutter!
A manatee tail is called a paddle, unlike the split fluke of a dolphin or whale. However, they use them to move in the same way, moving them up and down to locomote.
Manatees can also hear just like us. Although they don't have external ears like many other mammals, as aquatic animals, they don't need them. Instead, they have small pinholes on the side of their head that let in vibrations in the water that they then translate into sound.