says…
Pero Coordinating conjunction , mientras tanto , había Auxiliary cambiado Verb la Determiner situación Noun en Adposition el Determiner frente Noun del río Noun Paraná 
Proper noun .
Coordinating conjunction
Auxiliary
Verb
Determiner
Noun
Adposition
Determiner
Noun
Noun
Proper noun
But, in the meantime, the situation on the Paraná River front had changed. But , in the meantime , the situation on the Paraná River front had changed .
Words and sentences
había
first/third-person singular imperfect indicative of haber
cambiado
-
changed
la
-
the
en
- in, at, on
- in (a time)
- in (a language)
- used after some verbs and translated by various prepositions in English
- in (in various expressions)
el
masculine singular definite article; the
frente
forehead, brow
del
of the, from the (+ a masculine noun in singular).
Paraná
- Paraná (a river in central and southern South America)
- Paraná (a state of the South Region, Brazil; capital: Curitiba)
- Paraná (the provincial capital of Entre Ríos, Argentina)
- Paraná (a municipality of Rio Grande do Sul, Brazil)