This question was inspired by this other question and one of its answers. Essentially we have a lot of debris flying around in close proximity to Earth, and it is often going quite fast - fast enough to tear into or through somebody. Satellites and other such bodies have a lot of physical shielding, but even given any sort of armoring in a spacesuit, it just wouldn't be the same. So when astronauts go outside a station or a shuttle in a spacesuit, what keeps random debris from flying through their suits and into their bodies? How are they safe?
Safe is a big word, so can we first settle for safe enough that their EVA are worth the risk? OK, another big word in threat mitigation is risk management.
What this means is, that on top of larger debris being tracked by ground radars, their orbits predicted days in advance and assessing risk of these know debris entering the pizza box (imaginary square protected area around the station), EVA are scheduled to take place when and where the risk of collision with smaller (untracked) debris is predicted to be the smallest, and every step taken that they decrease exposure time. Obviously, this goes the same for space weather, for example scheduling during low Solar activity and during station's orbits that don't cross the South Atlantic Anomaly regions. And having backup EVA dates, if they have to be scrubbed for some unexpected reason, e.g. detected Solar flare pointing towards the Earth a day or so before the planned excursion, the station having to do orbital maneuvers to avoid larger debris,...
This risk management might mean taking fewer EVA and doing more tasks during each excursion, keeping the number of EVA astronauts / cosmonauts to the minimum that can still deal with unexpected situations (that would be two in egress and one in the station as support crew, and ground stations tracking their progress and monitoring other sensor readings), determining and prioritizing tasks necessity, placing ingress / egress and work locations in station's wake or otherwise protected by station's own hardware to minimize exposure to highest relative velocity debris, including changing station's own configuration, like rotating solar arrays, and so on.
So while safe is a lot to demand, various risk management procedures work, and make EVAs safer.
Space is very big and even though there is a lot of junk, astronauts are small targets. Nothing keeps it from happening really.
We're looking for long answers that provide some explanation and context. Don't just give a one-line answer; explain why your answer is right, ideally with citations. Answers that don't include explanations may be removed.
IIRC, like the Apollo Lunar EVA suits, the ISS suits are multi-layered to give the best chance of mitigating impact of sub-radar sized flecks etc. Think of it as 'spaced armour' on a vehicle. Outer layer takes the big hit, spalls a bunch of lesser splashes towards next layer. Recurse until non-lethal...
Also, this is why so much emphasis has gone into the Canadarm and tele-operated 'robots'.