Afternoon is the time of day after midday or noon. Since people usually have lunch in the middle of the day, afternoon can be seen to be the time of day between lunch and dinner.
Your birthday is the anniversary of your birth. Birthdays happen once a year on the same date as you were born. You usually get together with your family and friends on your birthday, and have a party with cake.
Breakfast is the first meal of the day. You can have all sorts of different things for breakfast. Many people have cereal with milk or toast with jam or honey. Some people prefer a cooked breakfast with bacon and eggs. Other people might like waffles or pancakes.
And some people like a breakfast with almost everything, like in the picture.
Christmas is a celebration held on the 25th of December to mark the anniversary of the birth of Jesus Christ. Christmas is typically celebrated by getting together with your family to share a meal and give gifts.
When you like someone, you might ask them out on a date to somewhere nice like a restaurant.
Dawn is the name given to the time of low light around sunrise.
Day might refer to the time when the sun is up, for example, "my cat sleeps all day", or it might mean an entire 24 hour period, usually counted starting from midnight.
The opposite of day is night.
Dinner is the meal you eat at the end of the day, usually at around 5 or 6 o'clock. Dinner can be anything, but is usually some kind of meat and some vegetables.
Easter is a celebration that happens once a year, on the first Sunday after the first full moon after the vernal equinox. Easter usually falls in March or April. Easter celebrates the resurrection of Jesus Christ, although modern familes who aren't practicing Christians will use the event to hold a hunt for chocolate or plain Easter eggs with their children.
And also ...
Appointment, Brunch, Celebration, Century, Ceremony, Decade, Divorce, Eve, Everyday, Fete, Future, Gig, Minute (time), Now, Once, Premiere, Quest, Rally, Sometimes, Soon, Today, Tomorrow, Tonight, Trip (voyage), Week, Yesterday.