Questions & Answers about Hoje eu quero comer um ovo no café da manhã.
Hoje means today, and putting it at the beginning is very natural in Portuguese when you want to set the time right away.
So Hoje eu quero comer um ovo no café da manhã feels like:
Today, I want to eat an egg for breakfast.
Portuguese word order is fairly flexible here. You could also hear:
Eu quero comer um ovo no café da manhã hoje.
That is also correct, but starting with Hoje gives today a little more emphasis.
It can often be dropped, because the verb form quero already tells you the subject is I.
So both of these are correct:
Hoje eu quero comer um ovo no café da manhã.
Hoje quero comer um ovo no café da manhã.
In Brazilian Portuguese, people often use subject pronouns more than in some other varieties of Portuguese, so eu sounds completely normal and natural.