Translation:The grandparents look under the bed.
An example of what I was saying: You call your grandparents "abuelos". If I translate that to "grandfathers" when actually you were talking about your grandmother and grandfather, then I am incorrect because your grandmother is not a grandfather.
But If I translate that to "grandparents", then I am correct. So the safe translation is to just say grandparents.
Because the translation is just giving you the most common way it would be said in English. The "gist" if you will. The literal translation though is "underneath of" ...and that's fine because really, that's actually proper English.
"under the bed" is just short for "underneath OF the bed". Sure we drop words here and there but knowing what the proper way of saying it sure does help with translating Spanish since a lot of the rules of speaking and writing that we as English speakers have long since decided to ignore, are still abided by.
And by the way, I would say "under the bed". I'm not a grammar nazi. Just pointing some things out lol.
I could not find support for the belief that underneath is short for "underneath of". Can someone provide a good reference. Sure, if you want to talk about the bottom side of something, like a car, you can say "the underneath of the car". However, if I want to talk about the area below something I would say "under/underneath the thing", not underneath of.