Stripe paymentIntent vs Subscription?

Following a guide for my server (Firebase) they charge the user with :

const payment = await stripe.paymentIntents.create(
    {
      amount,
      currency,
      customer,
      payment_method,
      off_session: false,
      confirm: true,
      confirmation_method: 'manual',
    },
    { idempotencyKey }
  );

Now in all Stripe examples, they use something like:

const subscription = await stripe.subscriptions.create({
  customer: '{{CUSTOMER_ID}}',
  items: [{
    price: '{{RECURRING_PRICE_ID}}',
  }],
  add_invoice_items: [{
    price: '{{PRICE_ID}}',
  }],
});

I am trying to understand :

1. What this paymentIntent does ? and how it relate to a subscription ? ( for me it just charge the user and its not clear if this is one time charge or a subscription )
2. Where is the Product that I created in the dashboard fits here ? I have a subscription product on the Dashboard , i would like to subscribe to that product ID, and not set a new price.

Reading the docs doesn't help since it is full of so much information and options without a clean flow.