I have found the issue. It was a known issue of civicrm v5.25. Here is the details: https://github.com/civicrm/civicrm-core/pull/17164/files
"Invoices - print and email" has been appeared in the dropdown menu after implementing the patch. Thanks everyone for the help
Go to Contributions menu » Find Contributions (or use Advanced Search with Display Results as set to Contributions.
Search for the invoices you want to send by setting Contribution Status to Pending and any other criteria you need.
Select "all X records" or manually select the invoices you want to send from the result.
From the Actions menu, select ...