What the roots of a plant are in is usually called a substrate. This is not always the usual land: plants can be grown in coconut fiber, pine bark, moss, fired clay, stones, synthetic materials, or in an aqueous solution with electrolytes.
Versatile peat-based substrates are suitable for most plants. Unfortunately, the composition on the packaging does not distinguish between good and bad soil. Bad soil is light, red in color, water on it collects in balls, does not go inside for a long time, gurgles on the surface. Over time, such soil compresses into a lump, lags far behind the edges of the pot, deep grooves form around the perimeter. Water rapidly flows past the ground into the sump, the soil is not wetted, the plant dries up. Good soil is black-brown, quickly and evenly soaked with water, when it dries out, it changes slightly in volume.
The earth can be gently tamped with your fingers to push it between the roots, fix the plant vertically. It makes no sense to leave air pockets: the earth will settle after the first watering. To help the earth settle evenly, you can gently tap the pot on a horizontal surface or tap the side of the pot with your palm.
For some plants, you will have to search or even prepare a special mixture. For phalaenopsis (the most popular orchids), you need to buy pine bark and cut it into large cubes. Cacti and other succulents are planted in a mixture containing at least half of the baking powder: stones, coarse sand, lava chips, zeolite. For the Venus flytrap (insectivorous plant), you need to buy pure high-moor peat.