When can 'es' be used to replace 'sie' (she)/'er'?
Consider this sentence:

"Es stellte Heiner vorsichtig auf den besten Platz auf der Veranda"

In English it is translated as "She placed Heiner carefully on the best spot of the patio"

From what I know, 'es' means 'it' in English. Could someone clarify on when can it be used to mean 'er'/'sie'. Thanks in advance

Question

When can 'es' be used to replace 'sie' (she)/'er'?
Consider this sentence:

"Es stellte Heiner vorsichtig auf den besten Platz auf der Veranda"

In English it is translated as "She placed Heiner carefully on the best spot of the patio"

From what I know, 'es' means 'it' in English. Could someone clarify on when can it be used to mean 'er'/'sie'. Thanks in advance

Answer

Please always give context together with the question. Fortunately Google finds "Heiner, der Eimer" as well as the text.

The reason the text has "es" is because it refers to "das Mädchen" (that's why the context is needed, you don't mention "Mädchen" at all), which is grammatically neuter. The grammatical gender always determines which pronoun to use, though there's a tendency in modern German to switch to "sie" for "das Mädchen" at some stage. In older German you will always find "es".