Hi,

    env(Environment) in new API is to provide an encapsulation around cursor, user_id, model, and context, Recordset and caches.

It evades the use of infamous function signature def afun(self, cr, uid, ids, context=None): and in new API its def afun(self):

And if you want to call ORM method directly from an object you can use self.env['obj'].method instead of self.method

An environment wraps data for ORM records:

• 'cr', the current database cursor.

• 'uid', the current user id.

• 'context', the current context dictionary.

For more about env: Link

For getting the value of accumulated from last record of 'hr.prestaciones' you can use this script:-

payments = self.env['hr.prestaciones'].search([])[0].accumulated

Hope this helps.