Farine de Blé Type 45
This is a category of French white flours that are made from just the endosperm of the grain (in French, this is called "l'amande du grain".)
Flours in this category are very smooth and fine, and will mix with a liquid without producing almost any lumps.
As a general summary, this type of flour includes those flours for cakes, crêpes, pastries, sauces and waffles.
In this category, the following flours are considered "farines supérieures" or "de luxe" ("farines supérieures" are always Type 45 flours.)
Farine de gruauThis is the finest wheat flour, made from soft wheat with 11% gluten. It can be used for raised pastry doughs, brioches, flaky pastries, sweet rolls, etc. It rises well.
Farine tamiséeTamisée means "sifted." It is also referred to as "fluide" or "extra-fluide." It is good for thickening sauces and making crêpes.
Farine à gâteauxCake flour. Can be used for cakes, brownies, pizzas, etc.
Farine avec poudre levanteThis is self-rising flour, meaning it has baking powder in it. Can be used for cakes, brownies, pizzas, etc.
Farine pâtissièrePastry flour. It is somewhat higher in gluten than cake flour. Rises well.
You can substitute Type 55 or all-purpose flour or plain flour, just sift well. Many French usually make an effort to buy a Type 45, though, for brioche and flaky pastry.