"The hospital is here."
Translation:El hospital está aquí.
What do you mean by "easy rule about accents"?
Accents in Spanish serve two different purposes:
1.) To indicate an emphasis that differs from the rule.
The rule is that words in Spanish without an accent have their emphasis (stress) on the last but one syllable, if the word ends in "s", "n" or a vowel, and on the last syllable else. If a word is to be pronpunced differently than according to this rule, it gets an accent on the stressed syllable. So "teléfono" is pronounced "telefono". Without the accent it would be "telefono".
2.) some words carry an accent, even though they are emphasized completely regular (or have only one syllable). This is in order to distinguish between pairs of words that would else be written identically. Examples are "el" ("the") vs. "él" ("he"), "si" ("if") vs. "sí" ("yes").
There is no rule for that. You simply have to learn the accents as part of these words.
You probably have typed "aqui" as the last word. But the word is "aquí". You may not have noticed there is an accent on the "i". It is not easy to see that, but it is important, because it tells that the stress is on the last syllable. Without the accent the stress would would be on the "a" according to Spanish pronunciation rules.
Duo's tip says we should use es for permanent things and esta for more temporary things. Now I want you to understand that the tip told me because I said "el hospital es aqui" thinking you know, hospitals are typically considered a permanent structure yeah? Still, the correct translation is "el hospital esta aqui" because apparently we're all in the military where the hospital tent is more temporary than a freaking building.
Forget about this "permanent/temporary"-thing. This is only a very crude rule of thumb, often more misleading than helpful.
"ser" is used for characteristics, whereas "estar" is used for conditions, emotional states and locations. For loactions you always use estar, no matter how permanent they might be.