What part is this?

Hello, I am new here. Can anyone tell me what this part is called? It sits up against the firewall on the drivers corner side. When I turn off the SUV, it makes a buzzing sound for the longest time? Thank you.

 

That's the charcoal canister for your emissions system (filters fuel gases from the tank). Totally normal for it to buzz, burp, and make other strange noises as the truck cools down, or even as ambient temperature around the truck changes during the day.

 

Thank you. I just had the engine block gasket replaced it was cracked. And when I got the SUV back from the garage, I noticed my air conditioning doesn’t work with a very strong smell of an Freon, after I turn it off. And this buzzing sound. None of which I had problem with before. So, kind of concerned……? I’m not a mechanic, nor do I work on the engine myself. So thank you for the response.

 

The A/C issues are unrelated (beyond the fact that someone was working on your truck) to anything going on with that box. That's not to say that the engine work didn't "break" something with your A/C, just that the two systems are completely separate and don't affect each other.