The signal delivered by a turntable is specific and must be processed upstream in order to be amplified. The very support that is vinyl implies a certain "transformation" of the signal that one must treat before amplification.
Some turntables incorporate phono preamplifiers - or RIAA correctors - natively, just like some amplifiers (dedicated phono input). For others, it will equip you with this device allowing the connection between any turntable and its dedicated sound system.
Be careful of their compatibility with your cell (MM or MC).