The Phono preamp is a component that boosts that tiny, weak signal from the turntable and converts it to a line level signal, the equivalent signal strength of, say, a CD player. Basically it jacks up the volume so you are able to hear it.
Without this phono stage you will hear pretty much nothing, even when you max out the volume.
Back in the good ol days every amplifier had a phono stage built in, however since CDs became a thing, many companies looking to reduce the cost of manufacturing stopped putting them on board.
But luckily now vinyl is back again (some would say it never went away)! You can find this phono pre-amp either in the amplifier, built into the turntable, or as an external device.
So depending on what kind of amplifier you are using and how much room you’ve got, you may need to make a decision on what kind of pre-amp you might need.