Easter Monday is on April 10 this year 0f 2023. It is when Easter, which falls on a Sunday, is publically honored as a holiday also.
The day is also known as Bright Monday, Dyngus Day, Renewal Day, and Wet Monday.
It is also Orthodox Easter Monday:
https://nationaltoday.com/orthodox-easter-monday/
https://nationaltoday.com/easter-monday/