How to close a site made on Joomla! for maintenance?

Question

Joomla

Good afternoon, dear toasters!
I made my own small site on joomla and since I am still a beginner in site building, I change the information on the site for a long time. Very often there are situations when it is necessary to close the site for a while, for example, to make some changes. If the site does not have traffic, then this makes no sense, you can not close the site. But if the site has good traffic, then it is better to close it for a while. May your visitors not witness your changes.
The hosting responded:
You can create a stub.
Create for example a default.php file with the desired content.
You can also create index.php, or index.html.
Or any other file to which you direct the indexing of the site through the .htaccess file.
Can you please tell me in detail how it is done?