It sounds like you want a regular haircut, layered on top with a tapered back/sides. Also called a businessman's haircut, a regular taper cut, a taper cut, a short back and sides and a few other names depending on location. A barber at Dollar Barber Shop or any barber shop should be able to do the haircut. If a guy is not presently wearing a regular haircut that he just wants trimmed back to how it was the last time it was cut, which the barber can figure out by asking how long ago the hair was last cut and figuring on an average rate of hair growth, a guy will have the best chance of getting the exact regular haircut he wants by using photos that show the style from the front, sides, back and top. A barber will usually ask if the guy wants the regular haircut short, semi-short, medium, long, extra long; if the back is to be blocked or tapered and the length the sideburns are to extend down the ears. The front and top will be cut an appropriate length and layered to complement the length of the taper on the back/sides-short, semi-short, medium, long, extra long etc- unless a guy states a specific length for the top and front or states not to trim the top/front this haircut. Other issues are the treatment of the lower edge of hair growth around the ear arches if it is to be different than usual for a short, semi-short, medium, long or extra long taper. Short tapers generally have the lower edge around the ear arches tapered to the skin. Semi-short sides can be tapered to the skin or outline edged around the ear arches. Medium and long tapers are usually outline edged around the ear arches but without cutting into the natural hairline, just to clean up the edge. Extra long tapers have a shaggy outline around the ear arches. Whether the lower edge of hair growth at the nape of the neck is blocked or tapered to the skin, it can be in a more squared off or rounded pattern. Short, semi-short and medium tapers are usually tapered to the skin. Long tapers can be tapered to the skin or blocked off. Extra long tapers are generally either blocked off or left with a shaggy block. With any length taper on the back/sides, the height up the back sides the taper goes from the lower edge of hair growth till it is well blended with longer hair from the top and the increase in length of the tapered hair on the back/sides till it meets the longer hair from the top can vary widely so it is best to use photos if a guy does not know how a particular barber usually tapers a short, semi-short, medium, long or extra long taper. This can be the most difficult aspect of a tapered haircut to describe to a barber without the use of photos.
Some barbers will significantly reduce volume by thinning the hair, others will leave the hair much fuller. If a guy has dense hair and wants to keep it fuller, he should indicate to go lightly on thinning as the hair can always be thinned further. A guy with less dense or less coarse hair might ask for the hair not to be thinned.
Suggest starting off with a regular haircut, around three to four inches on top, with a long taper on the back/sides with the lower edge at the back tapered down to around 1/4" at the lower edge of hair growth and then blocked off in a squared pattern with slightly rounded lower corners, an outline edge around the ear arches just at the natural hairline, medium sideburns.
Hair grows at an average rate of 1/8" per week. A photo is the best way to describe a style to a barber or stylist.