Meditation is often taken to mean stopping your thoughts, which is why many beginners quit when they can't. That isn't what happens, or what's asked. Counting breaths shows you what your mind actually does, and how quickly it wanders.
Your first day
Sit upright somewhere quiet for five minutes. No cushion or app required, a chair and a phone timer set before you start are enough. Spine straight but not rigid, eyes closed or gaze soft and down. Breathe normally, not deeply or slowly on purpose, since forcing the breath just gives you one more thing to manage. Count each exhale silently, one through ten, then start over at one. If you lose count, start again at one.
When you lose count or drift into a thought, which will happen constantly at first, don't treat it as a failure worth getting frustrated about. That reaction is actually the entire practice working correctly. Noticing the drift and returning to one is the skill, not staying uninterrupted the whole five minutes.
The thing most people miss
The return to counting after a distraction is the actual exercise. Your mind wandering is expected, and catching it is one repetition, the way one lift is one repetition in a set. A session full of interruptions can still be a good one, because every time you notice and start again you've practised the skill.
Getting annoyed at yourself is the common trap. It turns a practice into a test you keep failing, and that is what makes sits feel like they drag.
How you'll know it's working
The tell isn't fewer distracted thoughts during the five minutes. It's catching yourself breathing shallow during a stressful moment somewhere else entirely, and returning to your breath the same way you return to counting.
Body scanning, noticing physical sensation region by region instead of counting breaths, is the same skill of noticing and returning, turned toward the body. Once you can notice that your attention has drifted, you can use it in ordinary moments, like a tense meeting, without sitting down.