Whilst yes, there is a pebble beach here I can assure you that nobody ever comes here for a day on the beach.... ever. It is the windiest place on the island, one of the windiest places on earth and is hugely popular with wind surfers to the extent that world championships are held here in July of each year.
It's an easy pace to find, take the same exit for Vecindario / Atlantico off the motorway but head towards the ocean and the huge windfarm down there. Passing by banana plantations once at the village you'll the see "beach" is sign posted and you know you're there as there's a large parking usually full of vans with people getting their boards ready or packing them away, depending on what time you arrive.
Just opposite the beach is a concrete area that has been built for the partners or friends of the surfers who don't surf themselves and want to sunbathe. To avoid the constant wind there's a half dozen small walls constructed so you can soak up the rays without feeling the wind.
There's a nice instagram site dedicated to windsurfing at Pozo Izquierdo https://instagram.com/gcwindwavesfest
If you want to spend the day here then as you leave the motorway, first make a stop at Carrefour supermarket and buy all your snacks and drinks or mayube even eat in one of the restaurants there before going down to the beach. There's nothing in the way of facilities once you get down there unless there's a competition on.