What are the correct syntax and functions to use when retrieving data from Advanced Custom Fields in PHP?

When retrieving data from Advanced Custom Fields in PHP, you need to use the `get_field()` function provided by the ACF plugin. This function takes the field name or key as a parameter and returns the value of the field. You can also use the `the_field()` function to directly output the field value in your template.

// Retrieve data from a text field with the field name 'my_text_field'
$text_field_value = get_field('my_text_field');
echo $text_field_value;

// Output data from a number field with the field key 'my_number_field'
the_field('my_number_field');