NFC: is the abbreviation of Near Field Communication. This often touted feature is actually quite limited in Bluetooth speakers. It allows selected mobile phones to be paired with speakers through a quick touch. Since pairing is usually very simple, just press a button, once paired, the speaker will be remembered by your device, so it is not a must-have feature.
AptX: Another feature is limited to phones and devices around Apple. AptX is a codec (or a set of codecs) that is said to allow Bluetooth streaming with a resolution "close to CD quality". Apple products do not use AptX, but Android users may find that AptX can improve performance when paired with high-quality audio tracks and high-performance speakers. AptX Adaptive is the latest and greatest version of this codec, but both the source device and the Bluetooth speaker must support it to get any benefit.
Passive radiator: Passive radiator is a driver that is used to enhance the bass of speakers. In a sealed sound box (without portholes), a passive radiator responds to fluctuations in air pressure in the box to produce sound. Since the passive radiator does not require power from the amplifier, it has no magnets or voice coil, so it is lighter and smaller than traditional drivers. This saves space and cost, while improving the performance of the speaker.
Pairing: As far as Bluetooth speakers are concerned, pairing is to wirelessly connect the speakers to wireless devices via Bluetooth.
IPXX: IP stands for "ingress protection". This level indicates the resistance of the device to dust (the first number) and water (the second number). For example, an IP67 rated device is dust-proof and allows water to be submerged for 1 meter for 30 minutes. The higher the number, the better the protection effect, but for Bluetooth speakers, you should at least use IPX7. Stop it here to fully explain what it all means.