This is the 4364th most frequent Portuguese word.
aquáticas
"Aquáticas" means "aquatic" or "relating to water."
Here, 'aquáticas' modifies 'plantas' to describe their habitat or nature as related to water.
As plantas aquáticas crescem rapidamente nesse lago.
Aquatic plants grow rapidly in this lake.
In this sentence, 'aquáticas' qualifies 'atividades', indicating that these activities take place in or involve water.
As atividades aquáticas são muito populares durante o verão.
Aquatic activities are very popular during the summer.
Here, 'aquáticas' describes 'animais', referring to animals that live in or are associated with a water environment.