You can add web fonts to your pages using this API. What is needed is only adding a special stylesheet link to your pages. For example, using the following code:

<html>
<style>
body {
font-family: 'Tangerine', serif;
font-size: 48px;
}
</style>
<body>
<h1>Making the Web Beautiful</h1>
</body>
</html>


to set the font to Tangerine. It doesn’t matter if you don’t have this font on your local machine.

Actually if you open that stylesheet link and trace the font file, you may add that font to your local machine. But I don’t know whether Google allows this. Better view the license first.