This is the 41st most frequent Slovak word.
preto
"Preto" means "therefore" or "that's why" in English.
This usage of 'preto' is to indicate a cause-and-effect relationship, explaining the reason for staying at home.
On sa necíti dobre, a preto ostane doma.
He is not feeling well, and therefore he will stay at home.
Here, 'preto' is employed to explain the consequence of having a lot of work, which is her late arrival.
Mala veľa práce, preto prišla neskoro.
She had a lot of work, thus she arrived late.
In this context, 'preto' signals the reason behind making a mistake—her lack of preparation.