Learn Spanish (Latin America): ¿Invitas a tu hermano a la fiesta? - Are you inviting your brother to the party?

In Spanish, the simple present tense (like invitas, which means "you invite") is often used to talk about actions happening right now or in the near future. So, invitas can translate to "you invite," "you are inviting," or even "are you going to invite." You don't need a separate word for "are."

Why is there an a before tu hermano?

This is called the "personal a." In Spanish, whenever the direct object of a verb (the person receiving the action) is a specific person or a pet, you must put the word a right before it. Since you are inviting your brother, he gets the personal a.

There are two as in this sentence (a tu hermano and a la fiesta). Do they do the same thing?

Not quite! The first a is the "personal a" used because the brother is a person, and it doesn't translate to a specific word in English. The second a is a normal preposition that simply translates to "to" in English (to the party).

Why doesn't tu have an accent mark over the "u" here?

Without an accent mark, tu is a possessive word meaning "your" (tu hermano means "your brother"). If it had an accent mark (tú), it would be the subject pronoun meaning "you."