Fast Days, The Three Weeks

Hi Rabbi, I read that this weekend “The Three Weeks” begin. What does this mean? Thank you

If I take a fast upon myself from sun up to sundown, can I drink water/coffee, shower, brush my teeth?

I read that something called “The Three Weeks” is coming soon. What does this mean? I assume it refers to a special time in the Jewish calendar. Thank you.

Dear Rabbi, what is the Jewish fast day that I heard is observed on Friday, Dec. 25? Thank you.

Hi Rabbi, Does the Shabbat after Tisha B'Av have a special name and significance? Thanks and Shabbat Shalom.

Shalom aleichem Rabbi Lauffer. Thank you for answering my last question. If a 2 year-old niece wants to watch “Peppa Pig” on TV, is one allowed to put it on for her during the three weeks before Tisha b’Av, even though one will thereby hear the show’s music when he puts it on? Thanks a lot.

I heard that the “Three Weeks” is about to start. What are these three weeks all about? Thanks!