Questions & Answers about Oni diras, ke la vizo eksvalidiĝis; male, ĝi validas.
Oni is an impersonal pronoun. It means something like people, they, someone, or one, depending on context.
So Oni diras can mean:
- People say
- They say
- It is said
In everyday Esperanto, oni is a very common way to make a general statement without naming a specific person.
Because the sentence reports a current claim about a past event.
- oni diras = people are saying / people say now
- la vizo eksvalidiĝis = the visa expired earlier
So the tense change is completely normal:
- present for the act of saying
- past for the supposed expiration
Then ĝi validas goes back to the present, because it states the visa’s current status.
Ke introduces a content clause, like English that.
- Oni diras, ke la vizo eksvalidiĝis
= They say that the visa expired
In Esperanto, ke is normally stated explicitly. English often drops that, but Esperanto usually keeps ke.