I wonder if anyone can point out the name of this thing. I just bought Volvo XC60 2012 and found down I missed these parts from both side.

i start noticing this because when I drive and even road my front end bonnet makes a rattling sounds like something was loosened.

 

weather strip outer seal. Tasca parts has them for $5.92. https://www.tascaparts.com/v-2012-vo...gas/body--cowl

 

The rattle could be due to the bonnet standoffs in the front corners not being adjusted correctly and not touching/pressing against the bonnet or one may be too high, causing the other to have a gap. Easiest way to tell if they are adjusted correctly is get chalk or a crayon of a different color to your vehicle(white does not show very well on a white car) and rub it on the top of the rubber standoff. Close the bonnet. Open and see if you see a full circle on the bonnet on both sides. If partial circle, rotate the stand-off a quarter turn up and try again. If one is full circle and the other has nothing and the bonnet sits flush with the fender, raise the one not touching.
Do this until you are satisfied with the results. Do not try just turn them up for the sake of it or you will cause the bonnet to sit higher than the fenders or create stress on the latch.
if both are providing full circle but you can push down on the bonnet easily, raise both a 1/4 turn at a time until snug fit.

if after adjusting you still have a rattle, it’s probably the latch that needs to be adjusted. I would leave that to the dealer to do.

 

not sure if there's an adjustment for the latch. I just worked on my son's S40 and for that car, the hood latch bolts directly to the mount - no sliding adjustment.