Obstacles are layer based of course and generally can be thought of as swing highs and lows even if tiny or large, areas that were created with a V shape or fractal.

In the 2018 (wavefxv6) templates I have gone with purple of course but in this screenshot you posted we will define with green and brown as I did for those videos. On your screen shot there are three level 2 triggers and one level 1 trigger. The level 1 trigger simply means that the Green line has reached a potential turning point/location and that there are the 2 brown rejections of that same area to confirm that the Green has a great chance of turning there. Exactly where the price action is in your screenshot is a black trigger set up off of good brown line structure, the trigger being a mini double top, the brown structure being an area confirming double top (the green being at a potential location is the other boost but we can't see if that is true in the screenshot). The level 2 triggers are just black line triggers setting up at brown line turning points, so the next scale down, and based off of what is happening on the Green line.