In Spanish we refer to tilde diacrítica when we use an acute accent in a word to differentiate it from another word that is written exactly the same way but has a different meaning.
Examples of words with tilde diacrítica are:
tú vs tu (subject pronoun vs possessive adjective)
mí vs mi (pronoun vs possessive adjective)
A mí me gusta mucho el pescado a la plancha.I really like grilled fish. (Lit: grilled fish is pleasing to me)
más vs mas (adverb vs conjunction)
Pedro siempre ha sido más generoso que su hermano.Pedro has always been more generous than his brother.
Other words with tildes diacríticas are aún/aun, sí/si, té/te, dé/de, and él/el.