A polar or condensed range for example on AT7rainbow would include
hands like AA, TT, 77, A7, T7, and some mix of AK, AQ with backdoor flush possibilities. We might also have a small amount of hands like 76s, 98s, J9s, KQs, QJs, 44, 33, 22 and etc in our betting range.
Opposite of polar would be wide and that, on the same board, would look like all of the above at a considerable increase in frequency, plus many more combos of Ax, Kx, Qx, Jx, and etc.
In a polar or condensed range our value hands are limited to a small few set of hand combos, while in a wide range scenario, we can have many more combinations of value and the cutoff for what qualifies isn't as cold cut.
It's actually an important skill to know when a betting or checking range should be wide or narrow, and is an important concept worth exploring.