Have you tried help?

name = fields.Char(string='Name', help='Enter your name')

Bootstrap tooltips are used here. so you can have a look at bootstrap tooltip examples. from this link.

https://www.w3schools.com/bootstrap/bootstrap_ref_js_tooltip.asp

eg:

setTimeout(function () {
    if (!show_tooltip) return;
    $target.tooltip({title: _t('Double-click to edit'), trigger: 'manuel', container: 'body'}).tooltip('show');
    setTimeout(function () {
        $target.tooltip('destroy');
    }, 800);
}, 400);

Hello Samo,
Yes I tested "HELP" - But I want to display in the tooltip the content of "descrition of projet.tasks" which is an HTML zone and it does not work.
I said that I am a beginner on Odoo and that I modify the views by inheritance in "debug" mode. What I am trying to do is a presentation identical to what is shown when hovering over an area when you are in developer mode.

To be more precise, what I'm looking for in view_type = kanban & model = project.task is to display on the fly a "label" the description of the task layout

Thank you for your help
best regards