I have red blotch under my skin on both of my arms what is this my dad used to get this on his face. It takes a long time to clear up

Depending . Depending on your age and medications, this is often "solar purpura" which isnthe medical name for bruising. It is often due to age, medications, sun and genetics. It is typically a cosmetic concern. Some patients find arnica gel or vitamin k cream helpful when applied to the bruised areas to help them go away faster. Best to avoid scratching/trauma to these areas as you will from more bruises (purpura).