Do you really want to change the name of the columns or want them to be presented to your users in french? If so, what you want is to translate your module. To do so, you can follow the steps pointed here: http://stackoverflow.com/questions/11556502/how-to-translate-an-openerp-module

Well, In order to change the name of columns there is 2 way.

1.

You can inherit the column in your module and change the name. For example in Sale Order screen, there is column named "Date" now if you want to change that name to "Order Date" then you need to inherit that class in your module and just write following line,

'date_order': fields.date('Order Date', required=True, readonly=True, select=True, states={'draft': [('readonly', False)], 'sent': [('readonly', False)]}),

So when you update the module, This name will replaced on every place where this column taken.

2.

Inherit the View/XML file and just add new attribute "string" and give new name. So in this way, only at once place the name will be replaced. At other place the name will remain old. 

Hope this helps,