Follow given steps to add a new wizard for creating book rent records:

1. Add a new transient model to the module, with the following definition:

class LibraryRentWizard(models.TransientModel):
    _name = 'library.rent.wizard'

    borrower_id = fields.Many2one('res.partner', string='Borrower')
    book_ids = fields.Many2many('library.book', string='Books')

2. Add the callback method that performs the action on the transient model. Add the following code to the LibraryRentWizard class:

    def add_book_rents(self):
        rentModel = self.env['library.book.rent']
        for wiz in self:
            for book in wiz.book_ids:
                rentModel.create({
                    'borrower_id': wiz.borrower_id.id,
                    'book_id': book.id
                })  

3. Create a form view for the model. Add the following view definition to the module views:

 <record id='library_rent_wizard_form' model='ir.ui.view'>
    <field name='name'>library rent wizard form view</field>
    <field name='model'>library.rent.wizard</field>
    <field name='arch' type='xml'>
        <form string="Borrow books">
            <sheet>
                <group>
                    <field name='borrower_id'/>
                </group>
                <group>
                    <field name='book_ids'/>
                </group>
            </sheet>
            <footer>
                <button string='Rent' type='object'
                        name='record_book_rents' 
                        class='btn-primary'/>
                <button string='Cancel' class='btn-default' special='cancel'/>
            </footer>
        </form>
    </field>
</record>

4. Create an action and a menu entry to display the wizard. Add the following declarations to the module menu file:

<act_window id="action_wizard_rent_books" 
            name="Give on Rent"
            res_model="library.rent.wizard"
            view_mode="form" target="new" />
<menuitem id="menu_wizard_rent_books" 
          parent="library_base_menu"
          action="action_wizard_rent_books"
          sequence="20" />