This will alloy you to insert the alt text you write when you create the banner
you can change the div class to whatever you want "in this case div class is alt "
First create a smarty block name it as you wish and add to your home page "Important " after banner block
insert the script in the block
insert the style to your header of home page or in the css you created for your theme.
have a look at the attached pictures
This is just a free way to have text on your banners on homepage.... for better text on your banners there are some great addons on the marketplace.
You can use font-size: 28px; for Desktop devices and font-size: 14px; For Mobile devices
the style is up to you
.alt::after {
content: attr(data-alt);
position: absolute;
left: 0px;
bottom: 6%;
width: max-content;
max-width: 100%;
padding: 5px 2%;
text-align: center;
font-size: 28px;
color: #fff;
background-color: rgba(32,32,32,0.5);
word-break: break-word;
}