burn, bake, heat, roast
燒 centers on applying intense heat to transform something: burning, baking, heating, or roasting. The common thread is using fire to cook, consume, or alter a material.
燒 combines 火 (fire) with 堯, which likely contributes the sound and may relate to the idea of burning or heating. The exact historical development of 堯 is uncertain, but the phono-semantic structure is typical.
Fire 火 on the left and the tall shape 堯 on the right: imagine a towering bonfire used to bake, roast, and heat everything around it.
For ショウ, picture a show of flames: a spectacular fire show where things burn and roast. Show -> ショウ.