This is the 215th most frequent Estonian word.
pühapäeval
"On Sunday."
Here, 'pühapäeval' is in the adessive case, indicating the time when the activity occurred, which is on Sunday.
Pühapäeval käisin rannas.
On Sunday, I went to the beach.
In this sentence, 'pühapäeval' again indicates the specific time tied to the habit of resting, referring to Sundays.
Ma puhkan tavaliselt pühapäeval.
I usually rest on Sunday.
Here, 'pühapäeval' asks about plans or intentions related to Sunday, functioning as a temporal reference.