Typically it means that it's priced on the low end in a particular market.
There's nothing inherently "wrong" with your realtor advertising it as such.
In fact, in many areas, the so-called 'entry-level" houses are being sold
much quicker and have the largest percent appreciation each year.

Interior finish item upgrades (granite countertops, hardwood floors, 6-panel
solid doors, etc) may or may not make your house not be considered "entry
levels". About a decade ago I looked at a good number of houses that had
some of these ammenities, but they were still very much "entry level" to me
due to their market price and square footage. So the lesson is-- it's
unlikely that you'll be able to make your house a level or more about "entry
level" if that's what all the neighbor's houses are, generally speaking...

-Tim