These modules are great for use with Arduinos or other microcontrollers, say if you want a sensor node network or transmit data over a campus or town. The trade off is you need two or more radios, with matching frequencies. WiFi and BT, on the other hand, are commonly included in computers and phones.
The RFM69's are easiest to work with, and are well known and understood.
This is the 900 MHz radio version, which can be used for either 868MHz or 915MHz transmission/reception - the exact radio frequency is determined when you load the software since it can be tuned around dynamically. These are +20dBm FSK packet radios that have a lot of nice extras in them such as encryption and auto-retransmit. They can go at least 500 meters line of sight using simple wire antennas, probably up to 5Km with directional antennas and settings tweakings
All radios are sold individually and can only talk to radios of the same part number. E.g. RFM69 900 MHz can only talk to RFM69 900 MHz, LoRa 433 MHz can only talk to LoRa 433, etc.
Each radio comes with some header, a 3.3V voltage regulator and levelshifter that can handle 3-5V DC power and logic so you can use it with 3V or 5V devices. Some soldering is required to attach the header. You will need to cut and solder on a small piece of wire (any solid or stranded core is fine) in order to create your antenna. Optionally you can pick up a uFL or SMA edge-mount connector and attach an external duck.