[RadioKid]

"やすみです：YASUMI-DESU" indicates the status of the subject.
"会社はやすみです：KAISYA WA YASUMI-DESU"; The company is "OFF".

"やすみます：YASUMI-MASU" indicates the action of the subject.
"(私は)明日やすみます：(WATASHI WA)ASHITA YASUMI-MASU"; I will be absent from work tomorrow.

When you say "KAISYA WA YASUMI-MASU", it sounds strange like "the company will be absent from work".

>ちちは にちようび やすみます.

Good, meaning "My father takes off-day on Sunday".

>きょう だいがっくは やすみます.

きょう、だいがく　は　やすみます。

Strange. it should be "KYOU, DAIGAKU WA YASUMI-DESU.;The Univ. has no class today."

Do these help?