Il est Gallois.
Quelle est ton nationalite means 'What is your nationality'
It means "What is your nationality?"
"est de quelle nationalité ?" is a question asking about citizenship. You can typically find that on legal or administrative forms (state your country of nationality)
quelle heure est-il ? However nowadays we prefer to say 'have you got the time?' in French too rather than quelle heure est-il: Vous avez l'heure? Tu as l'heure? are more commun.
"quelle heure est-il ? means "what time is it?
"quelle couleur est-ce ?"de quelle couleur est cet objet ? : what colour is that object?
The literal translation is... "Nationality is"
Il est quelle huere? (What time is it)
What is the date? is the translation for Quelle est la date.
'mais quelle est cette ...' means but what is this (thing) / who is this (person).
Quelle est ta leçon préférée? means - what (or which) is your favourite lesson?
This means me too what is your nationality