This is the 776th most frequent Portuguese word.
altos
"Altos" in English means "high" or "tall" in the plural form.
In this sentence, 'altos' is used as an adjective indicating height.
Os prédios daquela rua são altos.
The buildings on that street are tall.
Here, 'altos' is part of an idiomatic expression 'altos e baixos,' meaning 'ups and downs'.
Ele viveu altos e baixos durante sua carreira.
He experienced ups and downs during his career.
In this case, 'altos' is used to describe elevated or high places.