Weihnachtsbaum.
ich liebe deine wienachten baum...
Because it depends whether it is a vowel or a consonant. For example 'a apple' is wrong. 'an apple' is correct. 'a book' is correct. 'an book' is wrong. The word that begins with a vowel like orange,...
Arvore de Natal.
The proper way to say it is 'Weihnachtsessen'. Weihnacht means 'Christmas', Abendessen means 'Dinner'.