It allows you to enter the phone number with the pattern you will create in the html input box.
HTML:
<input type="tel" value="" pattern="[0-9]{3} [0-9]{3} [0-9]{4}">
<!--
[0-9]{3} = 3-digit numbers between 0-9 must be entered
[0-9]{4} = 4-digit numbers between 0-9 must be entered
In addition, since we leave a space between these patterns, they should also leave a space.
If we put a period or dash in between, it must be entered in the same way.
Output: 123 456 7890
-->