There can be some dead grass, or grass/weeds less than 1 inch tall, if it is scattered. Otherwise, it should be landscaped to the topsoil. A landscaper usually uses an implement called a “power rake” to do this. With regard to the terrain, slope, rockiness, etc., of the site, the shape should look exactly how you want it prior to having sod installed. Having turf installed is comparable to having carpet laid: just like a lumpy floor without carpet will still be lumpy if you lay carpet on top of it, if there are holes or large rocks on the site before sod is installed, there will be holes and lumps in the yard after the installed grass settles.
Top Turf Sod Farm doesn’t do site preparation. However, we can recommend landscape companies that do.
A common mistake is to prepare the yard for sod and then wait several weeks before installing. It is important to install turf ASAP on newly landscaped ground, because rain or wind can create ditches and ruts and can wash or blow topsoil away.