The Reflection Render Channel stores reflection information calculated from the materials' reflection values in the scene. Surfaces with no reflection values set in their materials contain no information in the render pass and, therefore, render black.

The Reflection Render Channel is formed by multiplying the Raw Reflection Render Channel by the Reflection Filter Render Channel. So, while the raw reflection pass gives the full reflection of objects reflecting in the scene, the reflection filter sets how much of that reflection should come through in the composite. The two are multiplied together to create the V-Ray Reflection render channel, which gives a true representation of the reflection in the scene.

The Reflection Render Channel is a key component in the main Beauty Pass.

UI Path: ||V-Ray Node Editor|| > World > Render Channels > Beauty > V-Ray Reflection 

See the Render Channels page to find out where you can find these properties.

Channel Name – Customizable name for the render channel.

Enable Deep Output – Specifies whether to include this render channel in deep images.

Color Mapping – 

Consider For Anti-Aliasing – When enabled, anti-aliasing is used where possible.

Filtering –  Applies an image filter to this channel.

Vfb Color Corrections – Applies the post-render color adjustments made from the VFB.

Denoise – Enables the render channel's denoising, provided the Denoiser is enabled.