From the Super Mario Wiki
Flying ? Blocks are ? Blocks with wings. They are one of the many blocks in the Mario series. These blocks fly around from left to right or from up and down. They also appear in different colors. Some colors include red and yellow.
Super Mario World
Flying ? Blocks first debut in Super Mario World. They appear in few levels.
New Super Mario Bros.
These flying blocks reappear in New Super Mario Bros. where the red ones appear more frequently. This time, they fly around the map to a level. If Mario selects the level it is on, he can obtain a Fire Flower, 1-Up Mushroom, Mini Mushroom, Mega Mushroom, or a Blue Shell from the block. The yellow Flying ? Blocks also appear throughout levels, too.
New Super Mario Bros. Wii
In New Super Mario Bros. Wii, Flying ? Blocks make another appearance. This time, they function the same way in New Super Mario Bros..
Super Mario Galaxy / Super Mario Galaxy 2
A Flying ? Block
from Super Mario Galaxy 2
In both Super Mario Galaxy and Super Mario Galaxy 2, Flying ? Blocks make chirping noises similar to a real-world bird, and neither they nor their immobile counterparts could be Ground Pounded. Additionally, in Super Mario Galaxy 2, if Flying ? Blocks are hit, they will vanish right away, instead of turning into a normal Block.
Super Mario 3D Land
They later return in Super Mario 3D Land, and are found in several levels. In certain levels, it is required to ride on them to get a Star Medal.
New Super Mario Bros. 2
They appear again in New Super Mario Bros. 2. Now, they can appear as regular ? Blocks, and get wings to fly when are hit.
New Super Mario Bros. U
This blocks also appear in New Super Mario Bros. U with with the same functions as in previous games.
Mario Party 9
A flying ? Block in Mario Party 9 has the ability to spin the middle of it.
Names in other languages
||Bloque ? alado
||Winged ? block