Not much. Apply moisturizing lotions to keep it from drying, and this will help some. Aloe is considered helpful by some. If you have actual blistering, then this is a second degree burn, and should be treated with an antibiotic cream-neosporin- until it heals.
Sun burn. Keep sunburn cool with moist cool/cold compresses. Avoid alcohol containing products. Break off pieces of aloe vera plant & apply sap to skin. Consider non-steroidal anti-inflammatory meds to reduce pain. Don’t yank off peeling skin or burst blisters. Seek medical care for severe pain, fever, lack of improvement of symptoms within several days or if a large surface area is blistered.