What units are used by western airliners?
Airspeed, ground speed
Primary unit: km/h. Non-SI unit: knot.
In practise, knot is the main unit. At high levels, the Mach number is used, which is a measurement of speed relative to the local speed of sound.

Pressure
Pascal. Hectopascal is used for altimeter settings. In the USA they use inches of mercury.

Altitude
Primary unit: metres. Non-SI unit: feet.
In practise, feet is the main unit. Whether you say altitude or flight level depends on your reference air pressure.

Distance
Long: nautical mile. Short: metres. Vertical: foot.

Mass
Kilograms.

Volume
Litre or cubic metre.

Position
Latitude and longitude based on WGS84.

The above is according to ICAO Annex 5, which means that it is true for more or less all of the world. A few places prefer to deviate from the standard units, such as the USA, which uses a slightly different system.