world coordinates from local coordinates

you could make it a sequence of assignments

om = object_matrix
lc = local_coordinate
world_coordinate = om * lc

you'll have something like this:

import bpy

this_object = bpy.data.objects['Cube']

om = this_object.matrix_world
lc = this_object.data.vertices[1].co
world_coordinate = om * lc

print(world_coordinate)