@Oanh Ly - You will have to get your Google Calendar embed iframe code- follow these instructions:

https://support.google.com/calendar/answer/41207?hl=en

Amd follow these instructions to embed the iframe code into a Miro board:

https://help.miro.com/hc/en-us/articles/360017730993-Embedding-Media-to-Boards

Note that the Google Calendar won't open right inside of the board. Instead, you will see a thumbnail like so and will have to open it:

More info can be found into this post:

https://community.miro.com/ask-the-community-45/help-embedding-google-calendar-3943