The plus sign in CSS selector is used when you want to select an element right after the element specified on the left side of the plus sign. Have a look into the following CSS example.

p + h5 {
	color: blue;
}

If we have the following example HTML code. The color of the H5 will be changed to blue color.

<p>This is a paragraph.</p>
<h5>This is a sample h5 heading text.</h5>

However the above rule will not be applied for the following HTML code. Because for this example, after the p tag it is a div tag element, not an h5 element.

<p>This is a paragraph.</p>
<div>This is a div tag example.</div>
<h5>This is a sample h5 heading text.</h5>