Venom: What Does The Ending Really Mean?

All the way through Venom it's made blatantly clear that symbiotes are parasitic. When a host isn't up to snuff, they're killed almost instantly, while even the right match will slowly start to die if the alien isn't satiated. At one point Eddie Brock even takes an MRI scan and he's told that his organs are starting to fail him thanks to Venom feeding off them, which causes a pretty big bust up between the two.

This plot point is kinda just dropped from the movie after the scene is over though, and by the end Venom no longer seems to be having any negative effect on Eddie's health. While it's not outright explained, the most probable reason is that the symbiote now gets to eat a couple of brains now and then (as well as a few twinkies in between meals).

Eddie complains that he's "always hungry" which seems to be the cause for his ill health, and it's implied that as long as Venom gets to eat and is nourished, his host will be fine.