You cannot rig a 3D model in edit mode—edit mode is for modifying mesh geometry, while rigging (e.g., adding armatures, weight painting) requires object or pose mode.
Use edit mode to prepare your model for rigging: Clean up topology by adding edge loops around joints (knees, elbows) or fixing non-manifold faces—this helps the mesh deform naturally when rigged.
For beginners, edit mode is key to fix basic issues first: Merge overlapping vertices or fill small holes. This prevents errors when attaching the armature to the mesh in object mode.