WP_Query for a taxonomy with different taxonomy types

You can create a taxonomy query. Assuming that “curso” is the term slug, it would look like this:

$query = new WP_Query( array(
'post_type' => 'obras_en_curso',
'posts_per_page' => 4,
'tax_query' => array(
    array(
        'taxonomy' => 'casa_unifamiliar',
        'field'    => 'slug',
        'terms'    => 'curso',
    ),
  ),
) );

For more information, see: https://codex.wordpress.org/Class_Reference/WP_Query#Taxonomy_Parameters