What does 10x4 truck mean?

Answer 1

It has 5 (five) axles, and can have anywhere from 14 to 18 wheels. 4 (four) of the wheels, on 2 (two) axles are drive wheels. It's not like a ordinary 18-wheeler semi, It has no 5th wheel but can pull a trailer with a pindle hitch

Answer 2

As stated already, five axles total, with two providing power. In a configuration like this, you'll be talking about a single vehicle (straight truck), which will typically either have two lift axles, or will be a twin steer with an additional lift axle.