Ashes are the black and grey residue that is left after a fire. Ash is also thrown out in large quantities from volcanoes. Some ash, called charcoal, can be used to draw with.
A crash is a loud noise, usually made when something hits something else. You might drop saucepans to the floor with a crash. Cars can crash into things. The photo is of a wave crashing into the shore.
Your eyelashes are hairs that grow on the edges of your eyelids. Eyelashes protect your eyes, by stopping dirt and dust from getting in your eyes.
A flash is a bright light that you only see for a very, very short time. When you take a photo with a camera in dim light you usually use a flash to light the objects in the photo up so you will be able to see them. A flash can also be used to describe something you only see for a very short time, or didn't quite see clearly, as in "I saw the rabbit flash by".
Ganache is a mix of chocolate and cream. It can be used as frosting or filling for pastries and confectionary. It is made by pouring warm cream over diced chocolate and then stirring them together. Ganache is usually made with two parts chocolate to one part cream for filling, and equal parts for frosting or a glaze.
A gash is a large, deep, jagged wound. The dog in the picture has had a gash on his face stitched up.
When you mash something, you change its consistency to be soft and mushy, but not completely smooth. The most common kind of food that is mashed is boiled potato, which is mashed with milk and butter and called simply mashed potato.