Can 'bom dia' mean 'good afternoon'?

Answer 1

No. The English equivalent of the Portuguese greeting 'bom dia' is the phrase good day, or good morning. But the morning extends until after the lunch, and siesta. And so it may seem as though 'bom dia' also means 'good afternoon'. The greeting boa tarde, which means 'good afternoon' or 'good evening', begins after the siesta. It's just a different way of deciding when morning, evening, and night begin and end.