I need to create a six sided cube with text on one side. Will Dimensions be the right app for me to create this element?
Yes, you can do that with Dimension.
It already contains a ready made cube, so you won't have to import a separate .obj.
As for the text, on a side, you will be able to use a "decal", after you filled your cube with a material (say - plastic or wood)
The text will be added on top of your material after having transformed your cube into a standard model
the icon just before the colour swatch
The decal will be a graphics created in another software (eg: illustrator)
Another method could be to add some "flat text" (no "z" dimension) manually on top of the object, and although you can do that directly in Dimension using the "text" object (see the object above the cube in the screenshot) it will be more fiddly to place accurately. I suggest the first version.
It will show as this: