Show/Hide Field

I have a toggle which once switched to Yes, I want it to show a field that's just below it. but if left on No, the field should stay hidden.

How do I accomplish this?

Dear @Viorel,
With JavaScript, something like that should work:

fd.spRendered(function() {

    function hideOrShowField() {
        if (fd.field('YesNo').value) {
            // Show the MyField field
            fd.field('MyField').hidden = false;
        } else {
            // Hide the MyField  field
            fd.field('MyField').hidden = true;

    // Calling hideOrShowField when the YesNo value changes

    // Calling hideOrShowFieldon form loading


More examples of working with fields here - Work with SharePoint form fields in JavaScript — SharePoint forms