Why doesn't it accept "your train is this way?" Does "aqui" mean your train is here, as in arriving, or a statement to direct where the train's location is?
The root verbs are "ser" and "estar".
"Es" is the third person or the formal you conjugation of "ser", and would translate as 'he/she is' or 'you (formal speech) are'. The verb "ser" (to be) is used to describe things that are permanent or often unchangable. An example would be "Él es un doctor" (He is a doctor). "Ser" would also be used to describe permanent characteristics, religions, nationalities. "Ser" is also used when talking about time (although the actual time may change, the 'idea of time' is permanent).
"Está" (note the accent over the 'a'; 'esta' = 'this'. When speaking, there be a little more emphasis on enunciating the á, I believe) is the third person or the 'formal you' conjugation of "estar", and would also be translated as 'he/she is' or 'you (formal speech) are'. The verb "estar" is used to describe things that are temporary. With the example sentence, "Tu tren está aquí.", it is saying "Your train is (temporarily) here." "Estar" is used to describe locations, emotions/feelings and apparently death (due to the Spanish concept of death being temporary condition due to reincarnation), as well as used with other verbs to create a present progressive verb tense (i.e.: "Yo estoy caminando" = "I am walking").
I have seen a rhyme to try to help remember this: "For how you feel or where you are, always use the verb 'estar'."
Hope this helps!
I typed "Your train is here" and it's not taking that answer for some reason.
How come sometimes "tu" doesn't have an accent mark? How do you know when to put it?