No idea...

I'm trying to nurse my Son's bonsai back to health. Probably should have picked a different plant to care for as a first attempt at house plants. Don't know what variety it is and it seems to be dying. The leaves are going brown and falling off.

Gaile wrote: Probably should have picked a different plant to care for as a first attempt at house plants

:huh:

Bonsai are NOT house plants - though there are some species that survive indoors.

Don't know what variety it is and it seems to be dying

Your plant is a podocarpus.

Hard to tell what is wrong with it without knowing how the plant is being taken care off.
Could be overwatering, not enough light, problem with the roots, bugs...