</br> mean empty element?

Answer 1

no. "br" means break, because it breaks a line.

Ex.:

<...>

This is a simple </br> interrupted.

</...>

Inside the code you will see a continuous line, but the result is.

This is a simple
text interrupted.

Answer 2

thank you

Answer 3

as indicated by its name BR means BReak, to insert a break in a line just like the enter button in WhatsApp.