Update of Moodle 2.3.2 to version 2.3.3

I updated my moodle 2.3.2 to 2.3.3 but at the end I got two messages: 

my database needs to be in unicode UTF-8. So I need to migrate but I don't know how to do it.

I should install the php_extension intl (I don't know how to do it).

Can anyone help, please?

Thank you.