This is the 1862nd most frequent Russian word.
отправлять
To send.
In this sentence, 'отправляю' (sending) is used to denote the action of dispatching a letter.
Я отправляю письмо другу.
I am sending a letter to a friend.
Here, 'отправляет' (sending) indicates the action of ensuring that the children go to school.
Она отправляет детей в школу.
She is sending the children to school.
In this example, 'отправляют' (sending) refers to the process of physically or digitally distributing invitations.