Probably the easiest way to do this is to connect to the database using MySQL Workbench or similar, and extract the data using a SQL query e.g.
select u.user_login, u.user_email,
m1.meta_value as first_name, m2.meta_value as last_name,
m3.meta_value as billing_codice_snep,
m4.meta_value as codice_snep
from wp_users u
left join wp_usermeta m1 on m1.user_id = u.id and m1.meta_key = 'first_name'
left join wp_usermeta m2 on m2.user_id = u.id and m2.meta_key = 'last_name'
left join wp_usermeta m3 on m3.user_id = u.id and m3.meta_key = 'billing_codice_snep'
left join wp_usermeta m4 on m4.user_id = u.id and m4.meta_key = 'codice_snep'
and then you can use Workbench’s export to save this as a CSV or XLSX.
I’m guessing that you have called your user meta fields ‘codice_snep’ and ‘billing_codice_snep’. If not, you’ll have to change the last two lines of the query with the correct user meta keys.