es un dia mu lindo
As a day or How is a day?
It would be es un dulce dia (with an accent on the I in dia). This is one of the exceptions where the adjective comes before the object.
It's a beautiful day.
Es un dia bonito.
es un buen dia
Approximately "It's a beautiful day."
The exact translation would be "Hoy es un dia glorioso" However, that's not the most common phrase in Spanish. Is more usual to say "Hoy es un gran dia"
There are two sentences: Eso es todo - That is all Tengan un buen día - (All of you) Have a good day.
it means: "today is a good day all that I need now is"
Es un dia bueno para ir a la playa.
I hear lots of people say "Que tengas un bonito día." which literally means "That you have a pretty day." The formal of this phrase would be "Que tenga un bonito día." which you would say to someone older or in a higher position than you (like an employee to a customer, or a child to another child's parent, etc.) In fact, the Question concerns a statement, not a wish, so: Es un buen dia/un dia agradable = It's a nice day.