TimeHack converts time from four-digit "military time" to the more standard civilian time using AM and PM and vice-versa. When converting from civilian time, you can also tell TimeHack to convert from a time using the general time of day (e.g. '3:00 in the evening') instead of saying 'AM' or 'PM'.
“Alexa, ask TimeHack and Tell me what time 3:00 is in military time”