dump1090 is software that will decode ADS-B transmissions from nearby aircraft. ADS-B transmissions include information like aircraft tail number, latitude, longitude, airspeed and other telemetry data.
Your degree of success will depend on which SDR device you have. The NooElec NESDR Mini 2 is cheap and pretty good, though.
brew update
and then brew install librtlsdr
.git clone https://github.com/antirez/dump1090.git
cd dump1090
and then run make
. You should soon have a dump1090
executable in the current directory../dump1090 --interactive
.