It should be easy but it's often a pain. Most multi-conductor cables are colour coded, so it should be a snack to connect each one to the appropriate pins of an RJ45 wall socket or whatever.
But some of the colours are often a bit hard to distinguish - especially in poor lighting, when you're crouched down behind a desk or in some other awkward location.
It is surprisingly easy to mistake the blue-and-white for the
green-and-white, or the white-and-orange for the white-and-brown. And then you find that somebody's PC doesn't seem to want to talk to the network server, because you've swapped some of the pair returns...
Or you might be running a length of six-pair telephone cable
and need to make sure that you get the pairs properly matched at each end. It can be trickier than you'd expect.
What you need in your toolbox is a compact little signal
injector gizmo to squirt an easy-to-identify test signal along the conductors from one end, plus an equally compact little 'sniffer' or signal tracer gizmo so you can make sure which conductor is carrying the test signal at the other end.