Hi Cristian_Livella welcome to the forum
I’m not 100% clear what you’re after, but seeing “echo” suggests you want a page to update it’s content based on the current database value.
PHP can do “stuff” then output HTML. But once it is done outputting the page the only way to get fresh content is either to reload the page or use JavaScript.
Every 2-3 seconds seems a bit too often to be doing a full page reload.
So if this is what you are describing - i.e. updating a single variable value in a page - I suggest you look at finding a JavaScript method.
If this isn’t what you are describing, please try to explain again.