What does Halve leo mean?

For the road he preferred a halve leo over a normal can.

Dutch student slang. This is a Dutch word. You will hear it a lot at Dutch universities, student associations and in student houses.

It is bigger than a standard can, so you need fewer of them to last the whole party. A classic for the bike ride to a party. Pair it with a bvo and you are set. Also read about meter bier and pint.