Google font is not appearing on site

so Aleo is not in the set of Enfold implemented choice.
Go to the aleo page: https://fonts.google.com/specimen/Aleo

if you click on “select this font” on top right position there will be on the bottom a slide out window.
Click on that little dark gray slide out window. Now you see the implementing options.
You can customize the import options f.e. if you like to have the bold (700) font-style.

Standard: <link href="https://fonts.googleapis.com/css?family=Aleo&display=swap" rel="stylesheet">
@import rule:
@import url('https://fonts.googleapis.com/css?family=Aleo&display=swap');
or with bold font style:
@import url('https://fonts.googleapis.com/css?family=Aleo:400,700&display=swap');
the last rule could be placed f.e. on your child-theme style.css. ( Dashboard / Appearance / Theme Editor )

after that you can use the font for definitions in quick css as:
font-family: 'Aleo', serif;
so f.e.:

h1 {
font-family: 'Aleo', serif;
}

On GDPR Reasons it might be better to load the font locally.
Enfold got some Options for that:
All is said on f.e.: https://kriesi.at/documentation/enfold/typography/#register-additional-google-fonts-for-theme-options

if you like to have the newly added font in Enfold Font Choice you can do that via a littel snippet for child-theme functions.php:

add_filter( 'avf_google_heading_font',  'avia_add_heading_font');
function avia_add_heading_font($fonts)
{
$fonts['Aleo'] = 'Aleo:400,700&display=swap';
return $fonts;
}

add_filter( 'avf_available_google_fonts',  'avia_add_content_font');
function avia_add_content_font($fonts)
{
$fonts['Aleo'] = 'Aleo:400,700&display=swap';
return $fonts;
}

the font will be on the font list on the bottom of the lists.