This is the 3119th most frequent Portuguese word.
cai
"Falls" (third-person singular present form of "cair").
Here, 'cai' is used as the present tense form of the verb 'cair' to indicate something is falling down.
A colher cai da mesa.
The spoon falls from the table.
In this context, 'cai' describes the action of losing position or balance due to external force.
Se não segurar, o chapéu cai com o vento.
If you don't hold it, the hat falls with the wind.
Here, 'cai' portrays the repeated action of falling as a result of another action, indicating a consequence or result.