The dealers are supposed to put these plugs in after receiving the car. Many do not / or forgot to. 

The frame rails holes are used to secure the car for shipping with chain hooks. 
You might want to check your car to see if the plugs are installed in the 4 corners of car. 

Not putting the plugs in the frame holes can lead to water intrusion, noise, rust etc. 

This is a New Set of 4 Body Rail Plugs for a 2018 - 2020 Honda Accord 

They might fit older and newer units as well and perhaps other models too. 

WILL SHIP WORLDWIDE