So, you're new to Spelunky and keep dying to arrow traps without knowing how to counter them. If that's the case, then this guide is for you!
Arrow Traps Guide
The Principles of The Arrow Trap
Arrow traps are triggered when an object or entity passes in front of it. This does not include particles from explosions or blood drops. They have an activation range of about 6-7 tiles. A "tile" is basically just a block, think of Minecraft and you get the idea. The arrow it fires has a straight trajectory unless it hits something, which it will then bounce a few times before stopping. Whenever the arrow is blown up or has colided with an entity, it breaks and loses it's lethality. The arrow does 2 points of damage when fired or thrown.
How to Bait Out and Counter The Arrow Trap
How to bait out/negate the arrow trap.
Okay, so this is the section that explains how to actually get past arrow traps. There are a couple of different ways but the follow the same principles.
You can pick up objects like rocks or skulls and drop them in front of the arrow trap. DON'T throw them, just crouch and press your whip key to drop them down a hole or in front of them and the arrow trap will trigger.
You can pick up rats or the damsel when in the mines and when you pass in front of the arrow trap, the rat/damsel will take the hit instead of you. Note there will be some knock-back to this method so take that into account so you don't fall into an enemy or spike trap. In certain situations, when a spider is on the ceiling and you pass under the spider, it can trigger the arrow trap when it falls and die from it.
Using your tools and items
When you are faced with an arrow trap, you can drop a bomb in front of it to trigger it or explode it all together, or drop down a rope to trigger it. You can also shoot a weapon in front if it to trigger it or drop the weapon entirely.
I am going to explain an advanced strategy to dealing with arrow traps, whipping. You can whip an arrow out of the air if you are in the right position and time it right. If you pass in front of the trap between 5-3 tiles of it you can whip before going into it's range, and the arrow will collide with the whip and get smacked out of the air. Keep in mind the whip hitbox lingers so with some practice you can refine this strategy.