A fruit butter is a sweet spread

Spread (food)

A spread is a food that is spread with a knife onto bread, crackers, or other bread products. Spreads are added to bread products to provide flavor and texture, and are an integral part of the dish, i.e. they should be distinguished from condiments, which are optional additions...

 made of fruit

Fruit

In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

 cooked to a paste, then lightly sweetened. It falls into the same category as jelly and jam. Apple butter

Apple butter

Apple butter is a highly concentrated form of apple sauce, produced by long, slow cooking of apples with cider or water to a point where the sugar in the apples caramelizes, turning the apple butter a deep brown. The concentration of sugar gives apple butter a much longer shelf life as a preserve...

is a common example.

The fruit is cooked at first, but not too much, as the fruit will burn and soon lose its sugary taste. However, if done right, the newly made fruit butter, true to its name, has the same texture as, but different flavor than, regular butter.