what does it mean about 'Button connected to pin 3 and GND.'

hi, I am doing the emoji_button.ino project. I am confused about the 'Button connected to pin 3 and GND.'

Do I need to insert my Nano 33 BLE Sense board into the TinyShield? or use a jumper to connect Pin3 and GND? I am not sure. I will appreciate it if you could relpy.