This picture is from September 11th, 2020, when Biden, Cuomo, Schumer, and others met at Ground Zero in New York to commemorate the 19th anniversary of the 9/11 attacks. More pictures can be found on Schumer's Twitter post from that day. In these, you can see many other attendees wearing these blue ribbon pins on their lapels.
The blue ribbon represents solidarity with the relatives of the victims of these attacks, and is also worn in memory of the victims themselves. This is supported by this Guardian article from the 2014 anniversary, which notes that many attendees at the annual memorial ceremony wore such pins:
In New York, grieving relatives, many wearing light blue ribbons and
carrying pictures of their loved ones, gathered under overcast skies
for the annual 9/11 memorial ceremony.
[...]
“I just wanted one year to hear her name said correctly,” said Kirby,
who wore the blue ribbon on her lapel. She had lived in New York, but
moved to Florida after 9/11. It was her first time visiting the
grounds where her sister was killed.
This Daily Mail article from 2015 mentions that Rudy Giuliani is wearing the ribbon "in memory of those who perished".
