How to set my title and subtitle to H1-H5 without a new line

[Mandy-]

For example, I want to make the content easier for google to crawl therefore I need to set H1-H5 tag, but I don't want the content divided into two different lines, I want them to stay at the same line, what should I do?

Like this sentence: "Size: S, M, L, XL", I want to set "size" as H2 and set the rest of the words as paragraph, what should I do without dividing them into two lines?