For beginners, baking a prefab 3D model (usually texture baking like ambient occlusion or lightmaps) involves preparing the model (clean topology, UV unwrapping) in software like Blender or Unity, then using built-in tools to generate texture maps.
Baking transfers details (shadows, lighting) from a high-poly model to a low-poly prefab, making it efficient for real-time use (e.g., games). Start with simple types (ambient occlusion is easiest) and basic parameters (1024x1024 resolution, 2px margin) to avoid confusion.
In Blender, try the "Bake" panel in Render Properties—select "Ambient Occlusion" (Cycles renderer), assign a blank texture to the prefab, and click "Bake" for a straightforward first attempt.