This is an accepted solution.
Thanks for accepting as solution.
If you want to highlight few words in a sentence then you need to do the following
<h4>Happiness starts with a smile. <span class="highlight">Brighten</span> yours anytime, <span class="highlight">anywhere.</span> </h4>
Above is just an example. I put an span with 2 words using highlight class. so only that 2 words will highlight in that heading.
highlight will be a css class in your style.scss.liquid file in your theme.
Hope this works!