On Easter Monday, the Catholic Church celebrates what’s called “Monday of the Angel.” In many countries in Europe and South America, this day, also known as “Little Easter,” is a national holiday.

In a Vatican Radio recording in 1994, Pope John Paul II gave an explanation for Monday of the Angel:

“Why is it called that?” the pope asked, highlighting the need for an angel to call out from the depths of the grave: “He is risen.”

These words “were very difficult to proclaim, to express, for a person,” John Paul II said. “Also, the women that were at the tomb encountered it empty but couldn’t tell ‘he had risen’; they only affirmed that the tomb was empty. The angel said more: “He is not here, he has risen.”

https://www.catholicnewsagency.com/news/246699/the-catholic-church-celebrates-easter-monday-under-the-title-monday-of-the-angel