Hello Sonja.
Here in the US, Memorial Day is mainly (and supposed to be) about remembering members of the Armed Forces who lost their lives while in service. There will most likely be numerous TV shows and movies that have war themes getting rerun.
Also, most towns have a parade.
I'm sure you'll see many posts on FB from your US friends about Memorial Day.
However, it's also 'morphed' into weekend that is referred to as the "unofficial" start of summer, and many people host BBQs, or drive to the coast, to make their first trips to the beaches and boardwalks.