In a good restaurant, this is like an appetizer but, typically, much smaller. It would not be the equivalent of a French entrée, or appetizer, and is usually offered without charge. A canapé might be one example of an amuse-gueule.
This is the Russian term for hors-d'oeuvre. It's like telling someone what the Indians or Eskimos call their amuse-gueules . asdfjkl wishes to know what "amuse-gueules" means.
asdfjkl, I would describe it as a snack,appetizer (or nibbles, in colloquial English) served before a meal, usually not at the actual dinner table but rather in the lounge (where people are sitting/mingling before the proper meal), to keep the guests happy and stimulate their appetite, until the main meal is ready.
You find these mainly at receptions (no meal served there!) where people are standing up and chatting to one another.
Here are a few examples: here, here and here. I hope this helps