How are we able to see objects if they don't emit light

The main source of energy is sun photons i.e. source of light and heat are received by earth these light rays are responsible for our vision. As in mirror, when light falls on object it is reflected and when our eyes are in front of the object our eye lens makes an inverted image of that object on retina and then via optic nerves it is sent to our brain and our brain forms and erect image of the object and you see it for e.g. a banana or rainbow etc
. for proof in night are you able to see without artificial light source probably no.

Hope it works

You would see them through the light that they reflect; usually comes from the sun, or other luminescent objects. It wouldn't matter if they themselves don't emit light, because unless they absorb all of the light that reaches them, they should still reflect enough light to be perceived.

Yes, it is reflected light. They eye alone can't tell the difference between incident light, refracted light or reflected light. At night, close the curtains and turn all the lights out - everything disappears.

We don't "see" anything. We only see the reflected light. Everything we see is merely the light reflecting off an object.