This is the 2462nd most frequent Portuguese word.
cheio
Full.
Here, 'cheio' conveys the park containing many children, emphasizing an abundance.
O parque estava cheio de crianças brincando.
The park was full of children playing.
In this usage, 'cheio' refers metaphorically to someone having a lot of ideas or thoughts.
Eu estou cheio de ideias para nosso projeto.
I am full of ideas for our project.
In this sentence, 'cheio' is used to describe the glass being at full capacity with water.