http://stackoverflow.com/questions/37775255/django-how-to-translate-model-the-good-way

django.po

# SOME DESCRIPTIVE TITLE.
# Copyright (C) YEAR THE PACKAGE'S COPYRIGHT HOLDER
# This file is distributed under the same license as the PACKAGE package.
# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
#
#, fuzzy
msgid ""
msgstr ""
"Project-Id-Version: PACKAGE VERSION\n"
"Report-Msgid-Bugs-To: \n"
"POT-Creation-Date: 2016-06-12 10:06-0400\n"
"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
"Language-Team: LANGUAGE <LL@li.org>\n"
"Language: \n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=UTF-8\n"
"Content-Transfer-Encoding: 8bit\n"
"Plural-Forms: nplurals=2; plural=(n > 1);\n"

#: .\MonMagasin\models.py:9
msgid "category_name"
msgstr "Nom"

#: .\MonMagasin\models.py:10
msgid "category_image"
msgstr "Image"

#: .\MonMagasin\models.py:11
msgid "category_description"
msgstr "Description"

#: .\MonMagasin\models.py:17
msgid "category"
msgstr "Catégorie"

#: .\MonMagasin\models.py:18
msgid "categories"
msgstr "Catégories"

#: .\MonMagasin\models.py:22
msgid "product_name"
msgstr "Nom"

#: .\MonMagasin\models.py:23
msgid "product_image"
msgstr "Image"

#: .\MonMagasin\models.py:24
msgid "product_description"
msgstr "Description"

#: .\MonMagasin\models.py:25
msgid "product_price"
msgstr "Prix"

#: .\MonMagasin\models.py:29
msgid "product"
msgstr "Produit"

#: .\MonMagasin\models.py:30
msgid "products"
msgstr "Produits"

#: .\MonMagasin\models.py:37
msgid "sale_date_of_sale"
msgstr "Date de vente"

#: .\MonMagasin\models.py:43
msgid "sale_type_of_sale"
msgstr "Type de vente"

#: .\MonMagasin\models.py:46
msgid "sale"
msgstr "Vente"

#: .\MonMagasin\models.py:47
msgid "sales"
msgstr "Ventes"

models.py

from django.db import models
from datetime import date
from django.utils.translation import ugettext_lazy as _


# Create your models here.

class Categorie(models.Model):
    name = models.CharField(_('category_name'), max_length=55)
    image = models.CharField(_('category_image'), max_length=255)
    description = models.TextField(_('category_description'), max_length=500)

    def __str__(self):
        return self.name

    class Meta:
        verbose_name = _('category')
        verbose_name_plural = _('categories')


class Product(models.Model):
    name = models.CharField(_('product_name'), max_length=55)
    image = models.CharField(_('product_image'),max_length=255)
    description = models.CharField(_('product_description'), max_length=500)
    price = models.DecimalField(_('product_price'), max_digits=4, decimal_places=2)
    category = models.ForeignKey(Categorie, on_delete=models.CASCADE)

    class Meta:
        verbose_name = _('product')
        verbose_name_plural = _('products')

    def __str__(self):
        return self.name


class Sale(models.Model):
    date_of_sale = models.DateField(_('sale_date_of_sale'),default=date.today)
    TYPE_OF_SALE_CHOICES = (
        ('REGULAR', 'Régulier'),
        ('SPECIAL', 'Spécial'),
        ('OTHERS', 'Autres'),
    )
    type_of_sale = models.CharField(_('sale_type_of_sale'),choices=TYPE_OF_SALE_CHOICES, default='REGULAR', max_length=7)

    class Meta:
        verbose_name = _('sale')
        verbose_name_plural = _('sales')

    def __str__(self):
        return self.dateofsale.strftime(format='%A %w %B %Y')