Translation:The object is hot to the touch.
Also, 뜨겁다 can be for anything that makes you kind of directly feel the heart, even if you don't touch it.
Like, my wife will say "해 (the sun) 뜨겁다." and at first, I thought this was strange since I learned it as "hot to the touch" (and you don't touch the sun). A coworker said it's because you feel the effects right in your hair or head.
Not a native speaker, but 이 것, 그 것, and 저 것 are more common mostly due to their meanings. "This" (thing), "That" (thing), and "That" (thing, farther away)
것 is just "thing", while 물건 is "thing/object" (more physical, I'd guess), so you're not going to hear about it as much unless you're talking about an actual object. (just my speculation!)