Hello Salman Hossain,

First install this OCA App.

https://apps.odoo.com/apps/modules/12.0/web_ir_actions_act_multi/

after that write the return statement as follows

action_url = {
    'type': 'ir.actions.act_url',
    'url': '/website/pages',
    'target': 'self',
}
action_close = {'type': 'ir.actions.act_window_close'}

return {
    'type': 'ir.actions.act_multi',
    'actions': [action_url, action_close]
}

Regards