BOA dials use a rotary dial that tightens thin steel or polymer cables through the shoe, giving you a precise, even fit with just a twist. You can make micro-adjustments on the fly — loosen or tighten while riding — which is why they're the go-to closure system on most performance and race shoes across road, gravel, and mountain biking.
The big advantage over Velcro straps or laces is that combination of quick adjustment and even pressure distribution across your foot. Pull the dial up and the whole system releases instantly for easy exit at coffee stops or race transitions.
One thing to consider: single-dial shoes are common at lower price points, but dual-dial designs let you fine-tune the forefoot and midfoot separately for a more custom feel. Also, don't worry too much about durability — modern BOA dials like the Li2 and L6 are quite tough, and if one does fail, replacement kits are inexpensive and easy to install.