If you get air bubbles on the wall when you paint you should take a scraper and scrape off the bubbles before the paint dries too much.
Then after the paint dries sand the area down and clean the wall off making sure the sanding dust and any other particles are off the wall.
Wipe down the surface and be sure the wall or surface is dry and then repaint over the wall where the bubbles were.
If you're getting bubbles when painting it could be that the room is too humid or there is moisture coming into the walls from the outside.
Using a dehumidifier can help keep moisture out of the air and prevent air bubbles on the wall or surface you're painting.