Blender script to select the face of a cube with its normal facing the Y axis

blender_select_face_normal_y_axis.py

import bpy,bmesh

ob = bpy.data.objects['Cube']
bpy.ops.object.mode_set(mode='EDIT')
mesh=bmesh.from_edit_mesh(bpy.context.object.data)
for f in mesh.faces:
    if f.normal.y == 1.0:
        f.select = True

# trigger viewport update
bpy.context.scene.objects.active = bpy.context.scene.objects.active