A distraction technique is simply any activity that you engage in to redirect your mind off your current emotions. Instead of putting all your energy into the upsetting emotion, you reset your attention to something else. When you distract yourself, you are able to manage your strong emotions by bringing your focus elsewhere.
Some people enjoy mindful colouring as a way of distracting themselves from a cycle of negative thinking. Download a workbook which explains why this works and gives you some templates to get started on. Mindful colouring booklet.