Refers to a small piece broken off from a larger object.
Ten cuidado con esa brisura de madera, puede lastimarte si no tienes cuidado.
Be careful with that splinter of wood; it can hurt you if you're not careful.
Al caminar descalzo, sentí una brisura en mi pie que me hizo detenerme.
As I walked barefoot, I felt a splinter in my foot that made me stop.